A161557 a(n) = (n+1)*A000521(n), n>(-1).

1, 744, 393768, 64481280, 3457199880, 101229281280, 1999215843600, 29764163100672, 357255952575480, 3613417979904000, 31764402297844200, 248241326405529600, 1754542937994231528, 11366078355915079680, 68208141565173995280

Offset

-1,2

Comments

[Mathworld]: "Lehmer(1942) showed that (n+1)*C(n) == 0 mod 24 for n >= 1" Cf. A161395: (0, 31, 16407, 2686720, 144049995,...) = ((n+1)*A000521(n)) / 24.

Links

G. C. Greubel, Table of n, a(n) for n = -1..1000

Eric Weisstein's World of Mathematics, j-Function

Formula

a(n) = (n+1)*A000521(n), n > -1.

a(n) ~ n^(1/4) * exp(4*Pi*sqrt(n)) / sqrt(2). - Vaclav Kotesovec, Mar 06 2018

Example

a(2) = 64481280 = 3*A000521(2) = 3*21493760; such that 64481280 == 0 mod 24, where 64481280 / 24 = 2686720 = A161395(2).

Mathematica

a[n_] := With[{tau = Log[q]/(2 Pi I)}, SeriesCoefficient[Series[1728  *KleinInvariantJ[tau], {q, 0, n}], {q, 0, n}]]; Join[{1}, Table[(n + 1)*a[n], {n, 0, 50}]]  (* G. C. Greubel, Feb 25 2017 *)

Crossrefs

Cf. A000521, A161395.

Sequence in context: A178449 A178451 A066395 * A294182 A091406 A066396

Adjacent sequences: A161554 A161555 A161556 * A161558 A161559 A161560

Keyword

nonn

Author

Gary W. Adamson & Alexander R. Povolotsky, Jun 13 2009

Status

approved