OFFSET
-1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = -1..10000
FORMULA
Expansion of (eta(q) / eta(q^5))^6 + 125 * (eta(q^5) / eta(q))^6 in powers of q.
a(n) ~ exp(4*Pi*sqrt(n/5)) / (sqrt(2)*5^(1/4)*n^(3/4)). - Vaclav Kotesovec, Apr 01 2017
EXAMPLE
G.f. = 1/q - 6 + 134*q + 760*q^2 + 3345*q^3 + 12256*q^4 + 39350*q^5 + ...
MATHEMATICA
a[ n_] := With[{A = (QPochhammer[ q] / QPochhammer[ q^5])^6 / q}, SeriesCoefficient[ A + 125 / A, {q, 0, n}]];
PROG
(PARI) {a(n) = my(A); if( n<-1, 0, n++; A = x * O(x^n); A = (eta(x + A) / eta(x^5 + A))^6; polcoeff( A + x^2 * 125 / A, n))};
CROSSREFS
KEYWORD
sign
AUTHOR
Michael Somos, Jul 05 2014
STATUS
approved