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

Terms

a(0) =1a(1) =1a(2) =4a(3) =16a(4) =77a(5) =403a(6) =2228a(7) =12800a(8) =75653a(9) =457022a(10) =2809266a(11) =17514200a(12) =110480475a(13) =703850686a(14) =4522217364a(15) =29268545416a(16) =190645760149