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

Terms

a(0) =1a(1) =2a(2) =9a(3) =46a(4) =262a(5) =1590a(6) =10081a(7) =65986a(8) =442518a(9) =3024772a(10) =20996141a(11) =147603198a(12) =1048747751a(13) =7519252606a(14) =54332565330a(15) =395264527626