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

Terms

a(0) =1a(1) =2a(2) =4a(3) =16a(4) =80a(5) =480a(6) =3296a(7) =25152a(8) =209600a(9) =1884160a(10) =18110080a(11) =184898304a(12) =1994964736a(13) =22654449664a(14) =269855506944