OFFSET
0,2
FORMULA
a(n) ~ exp(Pi*sqrt(n/3)) * Gamma(1/4)^2 / (8 * Pi^(3/2) * sqrt(n)).
MATHEMATICA
nmax=60; CoefficientList[Series[Product[1/(1-x^(4*k+1))^2, {k, 0, nmax}], {x, 0, nmax}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Aug 27 2015
STATUS
approved