OFFSET
0,3
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..367
M. Kaneko and D. Zagier, Supersingular j-invariants, hypergeometric series and Atkin's orthogonal polynomials, pp. 97-126 of D. A. Buell and J. T. Teitelbaum, eds., Computational Perspectives on Number Theory, Amer. Math. Soc., 1998
Eric Weisstein's World of Mathematics, Eisenstein Series.
FORMULA
a(n) ~ 2 * Pi^5 * exp(2*Pi*n) / (27 * Gamma(1/4)^8). - Vaclav Kotesovec, Apr 07 2018
EXAMPLE
G.f. = q - 24*q^2 + 196812*q^3 + 38262208*q^4 + 40310333070*q^5 + 16012430173152*q^6 + ...
MATHEMATICA
a[ n_] := SeriesCoefficient[ (1 - 24 Sum[ DivisorSigma[ 1, k] x^k, {k, n}]) (1 + 240 Sum[ DivisorSigma[ 3, k] x^k, {k, n}]) / ((1 - 504 Sum[ DivisorSigma[ 5, k] x^k, {k, n}]) KleinInvariantJ[ Log[x] / (2 Pi I)] 1728), {x, 0, n}]; (* Michael Somos, Jan 15 2015 *)
CROSSREFS
KEYWORD
sign
AUTHOR
N. J. A. Sloane, Feb 28 2009
STATUS
approved