login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A302142 a(n) = (-1) * round(j((1 + sqrt(-n))/2)), where j is j-invariant. 1
-1728, -233, 0, 90, 539, 1539, 3375, 6511, 11663, 19897, 32768, 52512, 82306, 126616, 191658, 286008, 421407, 613808, 884736, 1263051, 1787217, 2508208, 3493226, 4830420, 6634880, 9056199, 12288000, 16579887, 22252407, 29715715, 39492794, 52248279, 68824132 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) is close to A056580(n) - 744.

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..200

Eric Weisstein's World of Mathematics, j-Function

EXAMPLE

   n | j((1 + sqrt(-n))/2) |   a(n)  | A056580(n) - 744

  ---+---------------------+---------+------------------

   1 |       -1728         |   -1728 |             -721

   2 |        -232.86...   |    -233 |             -659

   3 |           0         |       0 |             -513

   4 |          89.59...   |      90 |             -209

   5 |         538.90...   |     539 |              380

   6 |        1539.19...   |    1539 |             1454

   7 |        3375         |    3375 |             3328

   8 |        6511.17...   |    6511 |             6484

   9 |       11663.39...   |   11663 |            11648

  10 |       19897.28...   |   19897 |            19888

  11 |       32768         |   32768 |            32762

  12 |       52511.98...   |   52512 |            52508

  13 |       82306.31...   |   82306 |            82304

  14 |      126616.31...   |  126616 |           126615

  15 |      191657.83...   |  191658 |           191657

  16 |      286007.99...   |  286008 |           286007

  17 |      421407.46...   |  421407 |           421407

  18 |      613808.31...   |  613808 |           613808

  19 |      884736         |  884736 |           884736

  20 |     1263050.90...   | 1263051 |          1263051

  21 |     1787216.60...   | 1787217 |          1787216

  22 |     2508208.07...   | 2508208 |          2508208

PROG

(PARI) {a(n) = -round(ellj((1+sqrt(n)*I)/2))}

CROSSREFS

Cf. A000521, A056580, A305500.

Sequence in context: A232299 A280841 A305474 * A305494 A032354 A305475

Adjacent sequences:  A302139 A302140 A302141 * A302143 A302144 A302145

KEYWORD

sign

AUTHOR

Seiichi Manyama, Jun 04 2018

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 12 19:15 EDT 2021. Contains 343829 sequences. (Running on oeis4.)