OFFSET
0,2
COMMENTS
LINKS
G. C. Greubel, 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 - 2*q - 2*q^2 + 4*q^3 + 6*q^4 - 8*q^5 - 12*q^6 + 16*q^7 + 22*q^8 + ...
MATHEMATICA
a[n_]:= SeriesCoefficient[EllipticTheta[3, 0, -q]/EllipticTheta[3, 0, q^2], {q, 0, n}]; Table[a[n], {n, 0, 50}] (* G. C. Greubel, Dec 17 2017 *)
PROG
(PARI) {a(n) = local(A); if( n<0, 0, A = x * O(x^n); polcoeff( eta(x + A)^2 * eta(x^2 + A) * eta(x^8 + A)^2 / eta(x^4 + A)^5, n))}
CROSSREFS
KEYWORD
sign
AUTHOR
Michael Somos, Mar 16 2012
STATUS
approved