E.g.f. satisfies A'(x) = A(x/(1-x)).

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =15a(5) =111a(6) =1131a(7) =15081a(8) =253473a(9) =5220225a(10) =128886921a(11) =3749014251a(12) =126648293391