E.g.f. satisfies A(x) = (1 + 2*x)^(A(x)/2).

Terms

a(0) =1a(1) =1a(2) =1a(3) =6a(4) =17a(5) =220a(6) =939a(7) =20930a(8) =107393a(9) =3823416a(10) =20382195a(11) =1147905462a(12) =5519388225a(13) =515034742404