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

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =7a(5) =14a(6) =36a(7) =85a(8) =228a(9) =587a(10) =1612a(11) =4354a(12) =12166a(13) =33832a(14) =95876a(15) =271803a(16) =779287a(17) =2239584a(18) =6483386a(19) =18823945a(20) =54932299a(21) =160771540a(22) =472322632a(23) =1391323310a(24) =4110685812a(25) =12173949214a(26) =36141795088a(27) =107521223008a(28) =320531857144a(29) =957289637952