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A004422
Expansion of (Sum_{n=-inf..inf} x^(n^2))^(-21).
1
1, -42, 924, -14168, 169974, -1698312, 14692216, -112987776, 787175004, -5039316786, 29971442424, -167060546184, 878920016296, -4390113366408, 20920981191792, -95515527307648, 419275600889334, -1775001330567696
OFFSET
0,2
LINKS
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
KEYWORD
sign
STATUS
approved