Expansion of Product_{k>=1} (1 - x^k)^2.

Terms

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