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

Terms

a(0) =1a(1) =1a(2) =3a(3) =-3a(4) =-35a(5) =48a(6) =693a(7) =-1046a(8) =-16635a(9) =26328a(10) =442396a(11) =-720327a(12) =-12541509a(13) =20810208a(14) =371430414a(15) =-624691212a(16) =-11356013899a(17) =19293440712a(18) =355703260500a(19) =-609103135196