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

Terms

a(0) =1a(1) =1a(2) =3a(3) =15a(4) =88a(5) =594a(6) =4404a(7) =35260a(8) =300918a(9) =2714187a(10) =25715364a(11) =254752536a(12) =2629587927a(13) =28202629918a(14) =313575278100