Expansion of Product_{k>=1} (1 - x^k)^3.

Terms

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