G.f. satisfies: A(x) = ( A(x^2) + x*A(x) )^2.

Terms

a(0) =1a(1) =2a(2) =9a(3) =26a(4) =104a(5) =350a(6) =1321a(7) =4856a(8) =18667a(9) =71870a(10) =282368a(11) =1118470a(12) =4481428a(13) =18093104a(14) =73612825a(15) =301358656a(16) =1240776848a(17) =5133913326a(18) =21337546123a(19) =89037216384a(20) =372879415520