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

Terms

a(0) =1a(1) =2a(2) =6a(3) =30a(4) =170a(5) =1050a(6) =6846a(7) =46374a(8) =323154a(9) =2301618a(10) =16680246a(11) =122607342a(12) =911868282a(13) =6849381194a(14) =51885977838a(15) =395941193718