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

Terms

a(0) =1a(1) =1a(2) =2a(3) =9a(4) =40a(5) =192a(6) =963a(7) =5000a(8) =26649a(9) =144990a(10) =802023a(11) =4497150a(12) =25504380a(13) =146037955a(14) =843134220a(15) =4902661503a(16) =28686940053a(17) =168785282241a(18) =997968554037