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

%I

%S 1,744,393768,64481280,3457199880,101229281280,1999215843600,

%T 29764163100672,357255952575480,3613417979904000,31764402297844200,

%U 248241326405529600,1754542937994231528,11366078355915079680,68208141565173995280

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

%C [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.

%H G. C. Greubel, <a href="/A161557/b161557.txt">Table of n, a(n) for n = -1..1000</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/j-Function.html">j-Function</a>

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

%F a(n) ~ n^(1/4) * exp(4*Pi*sqrt(n)) / sqrt(2). - _Vaclav Kotesovec_, Mar 06 2018

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

%t 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 *)

%Y Cf. A000521, A161395.

%K nonn

%O -1,2

%A _Gary W. Adamson_ & _Alexander R. Povolotsky_, Jun 13 2009

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Last modified October 22 06:54 EDT 2019. Contains 328315 sequences. (Running on oeis4.)