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

Terms

a(0) =1a(1) =0a(2) =2a(3) =-3a(4) =2a(5) =0a(6) =2a(7) =-14a(8) =15a(9) =0a(10) =2a(11) =-22a(12) =2a(13) =0a(14) =84a(15) =-93a(16) =2a(17) =0a(18) =2a(19) =-38a(20) =172a(21) =0a(22) =2a(23) =-508a(24) =323a(25) =0a(26) =292a(27) =-54a(28) =2a(29) =0