OFFSET
1,6
FORMULA
a(n) ~ exp(2*Pi*sqrt(n/21)) * Gamma(3/7) * Gamma(6/7) / (4 * 3^(11/28) * 7^(3/28) * Pi^(5/7) * n^(25/28)). - Vaclav Kotesovec, Aug 26 2015
MATHEMATICA
nmax = 100; Rest[CoefficientList[Series[Product[1/((1 - x^(7k+3))*(1 - x^(7k+6))), {k, 0, nmax}], {x, 0, nmax}], x]] (* Vaclav Kotesovec, Aug 26 2015 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved