Product_{n>=1} 1 + a(n)*x^n = Sum_{n=-oo..oo} x^(n^2) = theta_3(x).

Terms

a(0) =2a(1) =0a(2) =0a(3) =2a(4) =-4a(5) =8a(6) =-16a(7) =32a(8) =-54a(9) =108a(10) =-184a(11) =368a(12) =-628a(13) =1296a(14) =-2160a(15) =4610a(16) =-7708a(17) =15848a(18) =-27592a(19) =58316a(20) =-98496a(21) =207576a(22) =-364720a(23) =756872a(24) =-1341970a(25) =2778300a(26) =-4918536a(27) =10443152a(28) =-18512788a(29) =37698416