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

Terms

a(0) =1a(1) =1a(2) =2a(3) =7a(4) =26a(5) =104a(6) =436a(7) =1894a(8) =8444a(9) =38418a(10) =177656a(11) =832548a(12) =3945156a(13) =18871524a(14) =91003360a(15) =441927367a(16) =2159282462a(17) =10607708284a(18) =52363342484a(19) =259601860898