G.f.: Sum_{n>=0} (x^(2*n-1) + 1)^n * x^n / (1 + x^(2*n+1))^(n+1), an even function.

Terms

a(0) =1a(1) =3a(2) =0a(3) =2a(4) =9a(5) =-12a(6) =8a(7) =12a(8) =-10a(9) =15a(10) =-36a(11) =46a(12) =-18a(13) =20a(14) =12a(15) =-82a(16) =101a(17) =-162a(18) =302a(19) =-168a(20) =-100a(21) =92a(22) =32a(23) =40a(24) =-244a(25) =351a(26) =-452a(27) =1052a(28) =-1528a(29) =1144