G.f. satisfies A(x) = 1 + x*(1 + x*A(x)^5)^3.

Terms

a(0) =1a(1) =1a(2) =3a(3) =18a(4) =106a(5) =720a(6) =5085a(7) =37493a(8) =284331a(9) =2204973a(10) =17404720a(11) =139369905a(12) =1129411314a(13) =9244823986a(14) =76326154857a(15) =634847759955