STATUS
reviewed
reviewed
proposed
editing
approved
editing
approved
editing
a[ n_] :=
SeriesCoefficient[ -20 + QPochhammer[ -q, q^2]^24 / q, {q, 0, n}]; (* Michael Somos, May 05 2016 *)
approved
editing
G.f. is Fourier series of a level 4 modular function. f(-1/ (4 t)) = f(t) where q = exp(2 Pi i t).
1/q + 4 + 276*q + 2048*q^2 + 11202*q^3 + 49152*q^4 + 184024*q^5 + ...
(PARI) {a(n) = local(A); if( n<-1, 0, A = x^2 * O(x^n); A = ( eta(x + A) / eta(x^4 + A) )^8 / x; polcoeff( 12 + A + 256 / A, n))}
approved