http://oeis.org/classic/A162584 GF = 1/prod(n=0, \infty, Theta3(x^(2^n))^(2^n) ) also GF = 1 / ( E1^2 E2^3 E4^6 E8^12 E16^24 E32^48 E64^96 E128^192 ... ) where EN = prod(n=1, \infty, 1-x^(N*x) ) and exponents are seq A042950 Neat!