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OEIS sequences needing factors

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Please check with corresponding OEIS entry and with factordb.com to make sure number still needed before embarking on a significant effort.


Mersenne Forum

Many of the listed sequences were subject to factoring efforts at Mersenneforum.org, a discussion board for those interested in factorization and primality searches. In particular, there is a thread about sequences that require some factorization in order to be extended, which comes with the comment:

The following table lists some OEIS entries for which computing further terms is blocked by finding at least one factor of an integer. In some, cases a complete factorization is required, in others only the smallest factor, or any factor.
The list is unlikely to be exhaustive nor does inclusion or exclusion from the list indicate any kind or importance or mathematical utility. As near as I can tell many of these sequences have no utility beyond their OEIS entry.
Rows marked with "*" indicate more terms are needed for the initial sequence lines in the corresponding OEIS entry. That is, the OEIS entry has (or should have) the "more" keyword. As above, it is not an indication of the importance of the sequence.
In some cases it is possible or likely that considerably more ECM effort has been expended than is indicated below.

ECM efforts

Sources

The following list contains some websites that track ECM or other factoring effort, which may not always be reflected on this page, but often are the sources of the ECM effort listed here:

  • yoyo@home performs ECM on a wide range of cofactors.
  • The most wanted Cunningham numbers can generally be assumed to have t70 ECM performed on them, as well as most base 2 Cunningham cofactors.
  • mersennus.net tracks ECM efforts on Fibonacci and Lucas numbers.
  • Studio Kamada tracks ECM efforts for near-repdigit-related numbers.
  • factordb does not track unsuccessful ECM efforts, but t-level of approximately the size of the largest known prime factor can be assumed at the least, barring their existence being known solely due to other methods (such as algebraic factorization, which may or may not be reflected accurately on factordb's "more information" subtab).
    • Some forms with known algebraic factorizations for a subset of their numbers:
    • Some forms with formulae for their divisors:
      • Fermat numbers (Fermat divisors)
        • It can be assumed a large amount of ECM has been run on all Fermat cofactors
        • Fermat divisors are primarily found through Proth Prime searches

The ECM efforts on this wiki page likely include efforts from the above links, and as such should not be backpropagated to those sources as if they had occurred twice. To be on the safe side, the total effort for a given composite number should be estimated as `max(other source, this page)`, unless a high degree of provenance can be established.

T-levels

To simplify communication of ECM progress, many use the "t-level" metric to condense the [<curves>@<B1>, ...] format down to a single number. For instance, the factoring program yafu can be used with the command line arguments -work <t1> and -pretest <t2> to run an optimal number and size of ECM curves on a composite with existing ECM t1 and desired finishing ECM t2.

Here's yafu's explanation of t-levels:

A note on the “t-level” terminology used in factor(). Something that has received, say, "t30", has had enough ecm curves run on it so that the probability that a factor of size 30 has been missed is exp(-1) (about 37%). Likewise, t35 indicates that factors of size 35 are expected to be missed about 37% of the time (at which point a 30 digit factor would only be expected to be missed ~5% of the time). t-levels are calculated from tabulated data extracted by A. Schindel from GMP-ECM in verbose mode. See also the GMP-ECM README file. I am unaware if t-level is universally accepted terminology or not, but others frequently use it (mersenneforum.org), and it is a handy way to talk about how much a particular number has been tested with ecm.

Conversion of ECM effort from <curves>@<B1> form to t-level form can be performed easily on Mersenneforum.org user WraithX's web page: ecmprobs.html.

Sequences in the OEIS

Cunningham numbers

Cunningham numbers are of the form , which have particular importance in number theory. More generally, b here may be fractional, giving rise to numbers of the form . Further extending this to quadratic irrational b leads to values of Lucas sequences (including Fibonacci, Lucas, and Pell numbers).

Cunningham numbers admit factorization via cyclotomic polynomials , and thus factorization of Cunningham numbers reduces to that of values of the corresponding cyclotomic polynomials.

id      size          description                       known ecm effort
-------------------------------------------------------------------------------- b = 2
A002185 C338          2^1123+1 or Phi_{2246}(2)         t65 [likely more], also needed by A002587, A002589, A046798, A046799, A053285, A054992, A057957, A059886, A069061, A085029, A086257, A112092, A250291, A274906, A295501, A366602, A366603, A366604
A002590 C311          2^1124+1 or Phi_{2248}(2)         t65 [likely more], also needed by A057940, A274903, A366605, A366606, A366607, A366608
A283931 C236        * 2^1151+1 or Phi_{2302}(2)         t65 [likely more],
A002184 C337          2^1207-1 or Phi_{1207}(2)         t65 [likely more], also needed by A002588, A005420, A046051, A046800, A046801, A049093, A049094, A053287, A059499, A075708, A085021, A086251, A097406, A112927, A237043
A003260 C297          2^1213-1 or Phi_{1213}(2)         t65 [likely more], also needed by A046932, A055061, A088863, A100730, A181046 
A038553 C284          2^1229-1 or Phi_(1229)(2)         t65 [likely more] 
A016047 C303          2^1237-1 or Phi_(1237)(2)         t65, also needed by A049479, A136030, A186283, A186522, A212953
A006514 C385          2^1277-1 or Phi_{1277}(2)         112000@26e7 [likely more], also needed by A085724
A057953 C212          2^1503-1 or Phi_{1503}(2)         t60 [likely more], also needed by A059890, A085033, A274908, A366651, A366652, A366653, A366654
A057936 C248          2^1509+1                          t60 [likely more], also needed by A274905, A366655, A366656, A366657, A366658
A002586 C1156         2^3968+1                          t30 [likely more], also needed by A366609
A073639 C984        * 2^4495-1 or Phi_{4495}(2)         t65 [likely more]
A096393 C1201       * 2^4844+1 or Phi_{9688}(2)         t15
A133485 C1510         2^5099-1 or Phi_{5099}(2)         t30 [likely more]
A133485 C1527         2^5099+1 or Phi_{10198}(2)        t30 [likely more]
A161508 C2941         2^9983-1 or Phi_{9983}(2)
A219461 Cmany       * 2^21700-1 or Phi_{21700}(2)
A046052 C1133         2^(2^12)+1 or or Phi_{8192}(2)    t55, also needed by A050922, A023394, A070592, A321213
A366671 C4880,C9844   2^(3*2^14)+1 or Phi_{3*2^15}(2)
A093179 C315653     * 2^(2^20)+1 or Phi_{2097152}(2) 
A199295 C5050446,C10100891   * 8^(8^8)+1 or 2^50331648+1 or Phi_{100663296}(2)
-------------------------------------------------------------------------------- b = 3
A002591 C265          3^691-1 or Phi_{691}(3)           t60 [likely more], also needed by A057952, A057958, A059885, A059891, A074477, A085028, A085034, A133801, A295500, A366575, A366576, A366660, A366661, A366662, A366663
A002592 C277          3^692+1 or Phi_{1384}(3)          t60 [likely more], also needed by A057935, A057941, A074476, A274909, A366577, A366578, A366579, A366580, A366664, A366665, A366666, A366667
A143663 C265          3^731-1 or Phi_{731}(3)           t40
A235365 C321          3^769+1 or Phi_{1538}(3)          t60 [likely more], also needed by A272069
A235366 C300          3^797-1 or Phi_{797}(3)           t60, also needed by A218356
A275377 C466          3^(2^10)+1 or Phi_{2048}(3)       t35
A113913 C317        * 3^2187+1 or Phi_{4374}(3)         t60
A200918 C479894     * (3^1006002-1)/1006003^2 or Phi_{1006002}(3)      2@1000,1@2000,1@5000,1@10000
-------------------------------------------------------------------------------- b = 10
A003021 C295          10^332+1 or Phi_{664}(10)         t60, also needed by A057934, A119704, A344897, A366668, A366669
A269503 C300          10^346+1 or Phi_{692}(10)         t40
A001270 C328          10^353-1 or Phi_{353}(10)         t60, also needed by A003020, A005422, A046053, A046107, A046412, A046415, A046416, A046417, A046418, A046419, A046420, A057951, A059892, A061075, A070528, A070529, A081317, A081318, A085035, A095370, A095413, A095414, A095417, A095418, A102146, A102347, A102380, A112505, A147556, A295503
A007138 C288          10^365-1 or Phi_{365}(10)         t60
A176973 C230          10^383-1 or Phi_{383}(10)         t60
A087020 C350          10^428+1 or Phi_{856}(10)         t60, also needed by A087021, A087022, A087023, A087024, A087025, A087026.
A003060 C336          10^439-1 or Phi_{439}(10)         t60
A046414 C449          10^467-1 or Phi_{467}(10)         t40, also needed by A046430, A095415, A268582
A147554 C301        * (10^471-1)/(10^157-1) or Phi_{471}(10)  t60, also needed by A110758
A046413 C509          10^509-1 or Phi_{509}(10)         t40, also needed by A196104
A072848 C315          10^528+1 or Phi_{1056}(10)        t45
A275381 C473          10^(2^9)+1 or Phi_{1024}(10)      t35
A038371 C950          10^(2^10)+1 or Phi_{2048}(10)     t35
A102050 C16385      * 10^(2^14)+1 or Phi_{32768}(10)    200@1e6, also needed by A185121
A122787 C354295       Phi_{3^12}(10) or Phi_{531441}(10)
A076670 Cbig          (10^9)^(10^9)+1 or Phi_{18000000000}(10)
-------------------------------------------------------------------------------- other integer b
A057939 C317          5^472+1 or Phi_{944}(5)           t35, also needed by A074478, A366615, A366616, A366617, A366618
A057956 C260          5^503-1 or Phi_{503}(5)           t60, also needed by A059887, A074479, A085030, A295502, A366611, A366612, A366613
A275378 C329          5^512+1 or Phi_{1024}(5)          t40
A250291 C364          5^521-1 or Phi_{521}(5)           t60, also needed by A218357
A057955 C281          6^421-1 or Phi_{421}(6)           t60, also needed by A059888, A085031, A274907, A366620, A366621, A366622, A366623
A057938 C246          6^421+1 or Phi_{842}(6)           t60, also needed by A274904, A366627, A366628, A366629, A366630
A275379 C777          6^1024+1 or Phi_{2048}(6)         t25
A366670 C3126         6^4096+1 or Phi_{8192}(6)
A057937 C314          7^388+1 or Phi_{776}(7)           t45, also needed by A227575, A366636, A366637, A366638, A366639
A057954 C299          7^389-1 or Phi_{389}(7)           t60, also needed by A059889, A074249, A085032, A366632, A366633, A366634, A366635
A218358 C315          7^431-1 or Phi_{431}(7)           t40
A275380 C861          7^1024+1 or Phi_{2048}(7)         t20
A274910 C319          11^317-1 or Phi_{317}(11)         t40, also needed by A366681, A366682, A366683, A366684, A366685
A062308 C334          11^326+1 or Phi_{652}(11)         t40, also needed by A366686, A366687, A366688, A366689, A366690
A218359 C344          11^331-1 or Phi_{331}(11)         t40
A275382 C482          11^512+1 or Phi_{1024}(11)        t35
A366712 C304          12^307+1 or Phi_{614}(12)         t40, also needed by A366713, A366714, A366715, A366716, A366720
A250288 C335        * 12^311-1 or Phi_{311}(12)         t60, also needed by A252170, A366707, A366708, A366709, A366710, A366711, A366718
A275383 C553          12^512+1 or Phi_{1024}(12)        t30,4600@11e6,1000@11e7 also needed by A366719
A302097 C184          13^256+1 or Phi_{512}(13)         t45
A218360 C308          13^417-1 or Phi_{417}(13)         t45
A302098 C265          14^256+1 or Phi_{512}(14)         t45
A324941 C239          17^212+1 or Phi_{424}(17)         t45
A218361 C200          17^243-1 or Phi_{243}(17)         t45
A218362 C254          19^239-1 or Phi_{239)(19)         t45
A218363 C381          23^307-1 or Phi_{307)(23)         t35
A218364 C262          29^223-1 or Phi_{223)(29)         t45
A128677 C21101        (102^(103^2)+1)/(102^103+1) or Phi_{21218}(102) 
A007571 C242          149^149+1 or Phi_{298}(149)       t45, also needed by A344859, A115973
A006486 C282          139^139-1                         t45, also needed by A334167
A177996 C408          192^193+1 or Phi_{386}(192)       t40
A298398 C276        * 2746511^90+1 or Phi_{180}(2746511) t45
-------------------------------------------------------------------------------- fractional b
A082869 C312        * 3^653-2^653 or Phi_{653}(3, 2)    t46
A122119 C680        * 2^1024+5^1024 or Phi_{2048}(2, 5) 100@10000,440@1e6 [1 factor is known, swellman]
-------------------------------------------------------------------------------- irrational b
A060385 C276          Fibonacci(1423)                   20158@11e7, 2000@26e7
A072381 C323          Fibonacci(1543)                   20158@11e7, 2000@26e7 (also needed by A278637)
A001578 C258          Fibonacci(1453)                   20158@11e7, 1000@26e7 (also needed by A060383, A139044)
A099954 C377        * F(1801) [F^R(1801) is semiprime]  20158@11e7, 6500@26e7, 650@85e7 (also needed by A072381)
A152012 C10449        F(49999)
A085726 C383          Lucas(1831)                       20158@11e7, 1000@26e7
A115101 C387        * Lucas(2602)                       7771@43e6
A246556 C228          Pell(631)                         7550@43e6
A250292 C271        * Pell(709)                         17768@11e7

Near powers, factorials, and primorials

id      size          description                       known ecm effort
-------------------------------------------------------------------------------- near-powers with b = 2
A099441 C191        * 2^634-635                         t45
A114970 C181        * 2^741+741^2                       t45
A099481 C249        * 2^827-827^2                       t45
A242273 C350        * 2^1152*1152-1                     t40
A242175 C425        * 2^1528*1528+1                     t40
A252657 C260        * 4^483-483                         t45
A242335 C266        * 4^437*437-1                       t45
A242204 C333        * 4^547*547+1                       t40    
A252789 C461        * 4^765+765                         t40
A252661 C334        * 8^369-369                         t40
A242271 C439        * 8^483*483+1                       t40
A242339 C526        * 8^579*579-1                       t40
A085745 C373        * 2^1239+1239                       7771@43e6
A165767 C449        * 2^1489-1489                       4590@11e6       also needed by A165768, A165769
A289117 C249        * 2^817*155+1                       t45
A100497 C436        * (2^361+1)^4-2                     t40
A268574 C258        * (2^428+1)^2-2                     t45
A269264 C232        * (2^385-1)^2-2                     t45
A360993 C367        * (2^406-1)^3+2                     t40
A360994 C321        * (2^355+1)^3-2                     t40
A268110 C327        * (2^543-542)*2^543+1               t41
-------------------------------------------------------------------------------- near-powers with b = 3
A252788 C669        * 3^1402+1402                       904@1e6,450@3e6
A114971 C205        * 3^428+428^3                       t45
A081715 C246        * 3^514+2                           4590@11e6,1000@11e7
A252656 C299        * 3^626-626                         t45
A080892 C314        * 3^658-2                           t45
A242274 C417        * 3^866*866-1                       t35
A242203 C430        * 3^894*894+1                       2350@3e6,1164@11e6
A242340 C492        * 9^512*512-1                       t40
A242272 C492        * 9^512*512+1                       t40
A252662 C239        * 9^250-250                         t45
A252794 C342        * 9^436+436                         t43
-------------------------------------------------------------------------------- near-powers with b = 5
A242336 C376        * 5^534*534-1                       t40
A252790 C536        * 5^766+766                         t40
A252658 C568        * 5^812-812                         t35
A114973 C607        * 5^868+868^5                       t35
A242205 C707        * 5^1006*1006+1                     t35
-------------------------------------------------------------------------------- near-powers with b = 6
A252791 C261        * 6^335+335                         t45
A242269 C342        * 6^436*436+1                       t40
A242337 C332        * 6^423*423-1                       t40
A252659 C481        * 6^617-617                         t40
-------------------------------------------------------------------------------- near-powers with b = 7
A252660 C325        * 7^384-384                         t40
A114974 C432        * 7^510+510^7                       t40
A242270 C612        * 7^720*720+1                       t35
A242338 C431        * 7^506*506-1                       t40
-------------------------------------------------------------------------------- near-powers with b = 10
A252795 C218        * 10^217+217                        t45
A252663 C269        * 10^269-269                        t45
A216378 C417        * 10^414*414+1                      t40
A242341 C599        * 10^596*596-1                      t35
A072288 Cbig        * 10^(10^100)+2, need factor > 16
A078814 Cbig        * 10^(10^100)-7, need factor > 16
-------------------------------------------------------------------------------- near-powers with b > 10
A099497 C414        * 182^183-183^182                   t40
A309747 C561        * 236^236+235^235                   t35
A219978 C237        * 115^115-114^114                   t45
A259026 C398        * 290*23^290-1                      t40
-------------------------------------------------------------------------------- near-factorials
A181186 C187          (2^104-1)*104!+1                  t45
A095194 C190          1000*114!+157                     t45
A095194 C189          1000*115!+167                     4480@11e6,1200@43e6
A085747 C171          106!+139                          t50
A152089 C174          4*109!+1                          t50             also needed by A180590
A100013 C178          110!+7                            7057@43e6
A063684 C182        * 118!+2                            17900@11e7,2000@26e7
A002582 C214          136!-1                            17900@11e7      also needed by A054991, A064145, A093082
A083340 C219          75!^2+1                           10908@2e8       also needed by A083341
A286181 C222        * 139!-1                            4480@11e6,3300@43e6  also needed by A286208
A002583 C242          140!+1                            17900@11e7,33500@85e7,1050@3e9      also needed by A054990, A064144, A064295, A078778, A181764
A078781 C272        * 154!-1                            t45             also needed by A080802
A098594 C2356       * 929!+1                            4590@11e6
A096225 C106520655  * 15750503!+1
-------------------------------------------------------------------------------- near-primorials
A002585 C196          523#+1                            2350@3e6,262@11e6,17900@11e7        also needed by A054988
A002584 C213          541#-1                            4480@11e6       also needed by A054989
A065314 C169          419#-421                          17900@11e7      also needed by A065316
A065315 C167          409#+419                          17900@11e7      also needed by A065317
A250293 C359        * 859#+1                            t40             also needed by A085725
A250294 C458        * 1091#-1                           4480@11e6
-------------------------------------------------------------------------------- other near-products of primes
A104358 C190          A104357(182)                      t45
A104359 C184          A104357(162)                      t45             also needed by A104360, A104361, A104362, A104363
A104366 C203          A104365(171)                      t45
A104367 C174          A104365(159)                      t45             also needed by A104368, A104369, A104370, A104371

Recurrence sequences involving factorization

id      size          description                       known ecm effort
-------------------------------------------------------------------------------- Euclid-Mullin sequences
A000945 C335          EuclidMullin52                    7557@43e6       also needed by A056756, A051318
A051308 C347          EuclidMullin[5]58                 7771@43e6
A051309 C313          EuclidMullin[11]56                7771@43e6
A051310 C204          EuclidMullin[13]37                t45
A051311 C232          EuclidMullin[17]31                t45
A051312 C284          EuclidMullin[19]51                t45
A051313 C355          EuclidMullin[23]38                t40
A051314 C390          EuclidMullin[29]57                t40
A051315 C240          EuclidMullin[31]38                t45
A051316 C247          EuclidMullin[37]43                t45
A051317 C362          EuclidMullin[41]38                t40
A051319 C194          EuclidMullin[47]36                t45
A051320 C283          EuclidMullin[53]49                t45
A051321 C258          EuclidMullin[59]49                t45
A051322 C416          EuclidMullin[61]43                t35
A051323 C200          EuclidMullin[67]43                t45
A051324 C287          EuclidMullin[71]45                t45
A051325 C439          EuclidMullin[73]45                t35
A051326 C292          EuclidMullin[79]32                t45
A051327 C296          EuclidMullin[83]65                t45
A051328 C743          EuclidMullin[89]79                4590@11e6
A051330 C261          EuclidMullin[97]52                t45
A051331 C334          EuclidMullin[131071]37            t40
A051332 C285          EuclidMullin[65537]71             t40
A051333 C168          EuclidMullin[257]45               t50
A051334 C328          EuclidMullin[8191]60              4590@11e6
A051335 C564          EuclidMullin[127]66               4590@11e6
A093782 C429        * EuclidMullin[8581]31              4590@11e6
A094152 C362          EuclidMullin[32687]51             t40
A261703 C183          EuclidMullin[139]35               t45
-------------------------------------------------------------------------------- aliquot sequences
A008892 C209          A008892(2146)                     t45
A014360 C185          A014360(1142)                     t45
A014361 C197          A014361(3486)                     t45
A014362 C182          A014362(1008)                     t45
A014363 C192          A014363(1035)                     t45
A014364 C181          A014364(2194)                     t45
A014365 C176          A014365(3839)                     t45
A152466 C1022         A152466(113)+1                    t20
--------------------------------------------------------------------------------
A000946 C332          prod(A000946(k),k=1..14)+1        1000@85e7
A005265 C367          prod(A005265(k),k=1..68)-1        4590@11e6
A005266 C211          prod(A005266(k),k=1..14)-1        17900@11e7
A057204 C1314         4*prod(A057204(k),k=1..47)^2+3    1000@1e6
A057205 C345          4*prod(A057205(k),k=1..24)-1      4590@11e6
A057206 C259          6*prod(A057206(k),k=1..17)-1      17900@11e7
A057207 C572          4*prod(A057207(k),k=1..41)^2+1    7600@43e6         cf. http://mersenneforum.org/showpost.php?p=334311&postcount=60
A057208 C414          prod(A057208(k),k=1..18)^2+4      1800@11e6
A084599 C211          prod(A084599(n),n=1..14)-1        t55
A102926 C472          prod(A102926(k),k=1..111)-1       2300@11e7
A102926 C432          prod(A102926(k),k=1..111)+1       2060@11e7
A124984 C923          prod(A124984(n),n=1..15)^2+2      t20
A124985 C257          8*prod(A124985(n),n=1..12)^2-1    t45
A124986 C554        * 4*prod(A124986(n),n=1..14)^2+1    t35
A124987 C366        * prod(A124987(n),n=1..15)^2+4      t40
A124988 C1197       * 4*prod(A124988(n),n=1..21)^2+3    t15
A124989 C853          100*prod(A124989(n),n=1..14)^2-5  t20
A124990 C224        * Phi_{12}(prod(A124990(n),n=1..8)) t45
A124991 C928          Phi_{5}(5*prod(A124991(n),n=1..34)) t20
A124992 C561          Phi_{7}(7*prod(A124992(n),n=1..21)) t35
A124993 C971          Phi_{11}(11*prod(A124993(n),n=1..14)) t20
A125037 C2117         Phi_{13}(13*prod(A125037(n),n=1..25)) 1000@1e6
A125038 C1164       * Phi_{17}(17*prod(A125038(n),n=1..14)) 1000@1e6
A125039 C745          (2*prod(A125039(n),n=1..29))^4+1  4590@11e6
A125040 C593        * (2*prod(A125040(n),n=1..10))^8+1  4590@11e6
A125041 C1056         (2*prod(A125041(n),n=1..20))^4+1  1000@1e6
A125042 C193        * (2*prod(A125042(n),n=1..4))^8+1   17900@11e7
A125043 C1057       * Phi_{9}(3*prod(A125043(n),n=1..21)) 1000@1e6
A125044 C2958         Phi_{27}(3*prod(A125044(n),n=1..23)) 1000@1e6,4590@11e6[need to confirm smallest before moving on]
A125045 C347        * prod(A125045(n),n=1..64)+2        4590@11e6
A217759 C561          4*prod(A217759(n),n=1..51)^2-1    890@43e6
A218467 C276          prod(A218467(n),n=1..19)+1        700@43e6
--------------------------------------------------------------------------------
A031439 C341          A031439(24)^2+1                   17900@11e7
A031440 C199          A031440(23)^2-2                   17900@11e7
A031442 C187          A151799(A031442(21))*A031442(21)-1 17900@11e7
A034970 C522          A034970(34)*A034970(35)-1         t30
A037274 C251          A037276^{118}(49)                 t61
A048986 C189          A048985^{281}(2295)               t45
A062962 C228        * A001697(13)                       t40
A082021 C194          A151799^{2}(A082021(22))*A082021(22)+2 t45
A082132 C356          A151799(A082132(22))*A082132(22)-2 t40
A096098 C1577         concat(A096098(n),n=1..182)
A120716 C1101       * A037279^{4}(8)                    4590@11e6
A191648 C3840       * A130846^{4}(7)
A130139 C364        * A037279^{6}(45)                   17900@11e7
A130140 C36562      * A361320^{7}(15)                   100@10000
A130141 C235        * A361580^{4}(35)                   4590@11e6
A130142 C1437       * A361581^{5}(45)                   t15
A195264 C178        * A195265(110)                      17900@11e7, also needed by A195265
A330291 C195          concat(A330291(n),n=1..27)/22349  t45

Other sequences

id      size          description                       known ecm effort
--------------------------------------------------------------------------------
A046461 C5497       * Sm(1651)                          4590@11e6
A079560 C200        * A005150(19)                       18340@11e7        also needed by A079562
A087552 C684          A065447(38)                       t25
A091335 C416        * Sylvester(11)                     17900@11e7      also needed by A091336
A323605 C785        * Sylvester(12)                     t25
A101757 C288        * Tribonacci(1091)                  4590@11e6
A108728 C168        * A019520(90)                       t50             also needed by A105388
A109757 C414        * tens_complement_factorial(191)+1  4590@11e6
A109758 C183        * tens_complement_factorial(112)-1  4590@11e6
A113773 C285        * A008352(13)                       4590@11e6
A153357 C169          A001008(391)                      7550@43e6,5000@11e7
A177892 C540        * A003010(10)                       17900@11e7
A249909 C310        * Euler(188)                        t45
A250295 C263        * A005165(150)                      4480@11e6,1290@43e6
A110760 C205        * A007942(56)                       t45
A110759 C214        * A173426(59)                       t45
A110757 C179          A000422(107)                      t45
A361624 C205        * A007942(56)                       17900@11e7