A004422 Expansion of (Sum_{n=-inf..inf} x^(n^2))^(-21).

1, -42, 924, -14168, 169974, -1698312, 14692216, -112987776, 787175004, -5039316786, 29971442424, -167060546184, 878920016296, -4390113366408, 20920981191792, -95515527307648, 419275600889334, -1775001330567696

Offset

0,2

Links

Seiichi Manyama, Table of n, a(n) for n = 0..10000

Formula

a(n) ~ (-1)^n * exp(Pi*sqrt(m*n)) * m^((m+1)/4) / (2^(3*(m+1)/2) * n^((m+3)/4)), set m = 21 for this sequence. - Vaclav Kotesovec, Aug 18 2015

Mathematica

nmax = 30; CoefficientList[Series[Product[((1 + (-x)^k)/(1 - (-x)^k))^21, {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Aug 18 2015 *)

Crossrefs

Sequence in context: A162411 A010994 A229564 * A020932 A264489 A036400

Adjacent sequences: A004419 A004420 A004421 * A004423 A004424 A004425

Keyword

sign

Author

N. J. A. Sloane

Status

approved