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

Terms

a(0) =1a(1) =1a(2) =4a(3) =4a(4) =-13a(5) =-81a(6) =-389a(7) =-198a(8) =7455a(9) =44515a(10) =198661a(11) =70243a(12) =-5428624a(13) =-40239313a(14) =-218619844a(15) =-408542577a(16) =3648305171a(17) =44441073999a(18) =339489511573