Product t2(q^d); d | 21, where t2 = theta2(q)/(2*q^(1/4)).

Terms

a(0) =1a(1) =1a(2) =0a(3) =2a(4) =1a(5) =0a(6) =2a(7) =1a(8) =1a(9) =2a(10) =4a(11) =1a(12) =1a(13) =3a(14) =0a(15) =2a(16) =2a(17) =2a(18) =2a(19) =3a(20) =1a(21) =4a(22) =4a(23) =0a(24) =7a(25) =4a(26) =2a(27) =4a(28) =5a(29) =1