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

Terms

a(0) =1a(1) =1a(2) =4a(3) =15a(4) =84a(5) =402a(6) =2520a(7) =13339a(8) =88484a(9) =494814a(10) =3395816a(11) =19657398a(12) =137999048a(13) =818024484a(14) =5836517808a(15) =35201610387a(16) =254231733188