OFFSET
0,4
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..10000
FORMULA
G.f.: Product_{i>0} (1 + Sum_{j>0} (-1)^j*j*q^(j*i)).
a(n) ~ (-1)^n * exp(2*Pi*sqrt(n)/3) / (6*n^(3/4)). - Vaclav Kotesovec, Oct 05 2017
MATHEMATICA
nmax = 50; CoefficientList[Series[Product[(1 - x^k) * (1 - x^(3*k)) / (1 - x^(2*k))^2, {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Oct 05 2017 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Oct 05 2017
STATUS
approved