OFFSET
0,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..10000
FORMULA
a(n) ~ (-1)^n * 49*exp(Pi*sqrt(7*n)) / (4096*n^(5/2)). - Vaclav Kotesovec, Aug 18 2015
From Ilya Gutkovskiy, Sep 20 2018: (Start)
G.f.: 1/theta_3(x)^7, where theta_3() is the Jacobi theta function.
G.f.: Product_{k>=1} 1/((1 - x^(2*k))*(1 + x^(2*k-1))^2)^7. (End)
MATHEMATICA
nmax = 30; CoefficientList[Series[Product[((1 + (-x)^k)/(1 - (-x)^k))^7, {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Aug 18 2015 *)
PROG
(PARI) q='q+O('q^99); Vec(((eta(q)*eta(q^4))^2/eta(q^2)^5)^7) \\ Altug Alkan, Sep 20 2018
CROSSREFS
KEYWORD
sign
AUTHOR
STATUS
approved