OFFSET
0,2
COMMENTS
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..1000
Michael Somos, Introduction to Ramanujan theta functions
Eric Weisstein's World of Mathematics, Ramanujan Theta Functions
FORMULA
EXAMPLE
1 + 3*x + 4*x^2 + 5*x^3 + 5*x^4 + 5*x^5 + 7*x^6 + 7*x^7 + 9*x^8 + 7*x^9 + ...
q^7 + 3*q^31 + 4*q^55 + 5*q^79 + 5*q^103 + 5*q^127 + 7*q^151 + 7*q^175 + ...
MATHEMATICA
nmax = 100; CoefficientList[Series[Product[(1 - x^k)^2 * (1 + x^k)^5 * (1 - x^(3*k)) / (1 + x^(3*k)), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Sep 08 2015 *)
PROG
(PARI) {a(n) = local(A); if( n<0, 0, A = x * O(x^n); polcoeff( eta(x^2 + A)^5 * eta(x^3 + A)^2 / (eta(x + A)^3 * eta(x^6 + A)), n))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Michael Somos, Aug 29 2013
STATUS
approved