OFFSET
1,4
FORMULA
a(n) ~ exp(2*Pi*sqrt(n/21)) * Gamma(1/7) * Gamma(4/7) / (4 * 3^(3/28) * 7^(11/28) * Pi^(9/7) * n^(17/28)). - Vaclav Kotesovec, Aug 27 2015
MATHEMATICA
nmax = 100; Rest[CoefficientList[Series[Product[1/((1 - x^(7k+1))*(1 - x^(7k+4))), {k, 0, nmax}], {x, 0, nmax}], x]] (* Vaclav Kotesovec, Aug 27 2015 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved