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A064001
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Odd abundant numbers not divisible by 5.
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6
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81081, 153153, 171171, 189189, 207207, 223839, 243243, 261261, 279279, 297297, 351351, 459459, 513513, 567567, 621621, 671517, 729729, 742203, 783783, 793611, 812889, 837837, 891891, 908523, 960687, 999999, 1024947, 1054053, 1072071
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Or, odd abundant numbers that do not end in 5.
All terms below 2000000 are divisible by 21 (so by 3). Moreover, except for a few, most are divisible by 231. - Labos E. (labos(AT)ana.sote.hu), Sep 15 2005
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REFERENCES
| David Wells, The Penguin Dictionary of Curious and Interesting Numbers, p. 169 (Rev. ed. 1997).
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LINKS
| Harry J. Smith, Table of n, a(n) for n=1,...,1000
C. Rivera, Puzzle 329. Odd abundant numbers not divided by 2 or 3.
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MATHEMATICA
| Select[ Range[ 1, 10^6, 2 ], DivisorSigma[ 1, # ] - 2# > 0 && Mod[ #, 5 ] != 0 & ]
ta={{0}}; Do[g=n; s=DivisorSigma[1, n]-2*n; If[Greater[s, 0]&&!Equal[Mod[n, 2], 0]&& !Equal[Mod[n, 5], 0], Print[n]; ta=Append[ta, n]], {n, 1, 2000000}] ta=Delete[ta, 1] - Labos E. (labos(AT)ana.sote.hu), Sep 15 2005
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PROG
| (PARI) { n=0; forstep (m=1, 10^9, 2, if (m%5 && sigma(m) > 2*m, write("b064001.txt", n++, " ", m); if (n==1000, break)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 05 2009]
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CROSSREFS
| Cf. A005231, A110585.
Sequence in context: A050517 A069304 A157664 * A029752 A043608 A134122
Adjacent sequences: A063998 A063999 A064000 * A064002 A064003 A064004
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KEYWORD
| nonn
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AUTHOR
| Harvey P. Dale (hpd1(AT)nyu.edu), Sep 17 2001
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EXTENSIONS
| More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Sep 28 2001
Further terms from Labos E. (labos(AT)ana.sote.hu), Sep 15 2005
Entry revised by N. J. A. Sloane (njas(AT)research.att.com), Mar 28 2006
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