G.f. A(x) satisfies A(x) = 1 + x/A(x)^2 * (1 - A(x) + A(x)^3).

Terms

a(0) =1a(1) =1a(2) =0a(3) =2a(4) =-3a(5) =12a(6) =-35a(7) =121a(8) =-413a(9) =1464a(10) =-5265a(11) =19249a(12) =-71236a(13) =266443a(14) =-1005511a(15) =3824055a(16) =-14641264a(17) =56389272a(18) =-218315173a(19) =849170605a(20) =-3316817080a(21) =13004273475a(22) =-51160638706a(23) =201901154910a(24) =-799059730844