a(n) = [x^n] Product_{k>=1} ((1 + x^(2*k-1))/(1 + x^(2*k)))^n.

Terms

a(0) =1a(1) =1a(2) =-1a(3) =-5a(4) =-1a(5) =31a(6) =65a(7) =-90a(8) =-641a(9) =-644a(10) =3329a(11) =11386a(12) =-1471a(13) =-87021a(14) =-164634a(15) =317935a(16) =1881471a(17) =1418719a(18) =-11370760a(19) =-33937951a(20) =17468929a(21) =294971868a(22) =468897758a(23) =-1304743033a(24) =-6275603903a(25) =-2804572819a(26) =42665919997a(27) =109181454826a(28) =-106020803386