G.f.: Sum_{n>=0} x^n * (1 - x^n)^n.

Terms

a(0) =1a(1) =1a(2) =0a(3) =1a(4) =-1a(5) =1a(6) =-1a(7) =1a(8) =-3a(9) =4a(10) =-4a(11) =1a(12) =0a(13) =1a(14) =-6a(15) =11a(16) =-11a(17) =1a(18) =7a(19) =1a(20) =-18a(21) =22a(22) =-10a(23) =1a(24) =-3a(25) =6a(26) =-12a(27) =37a(28) =-48a(29) =1