G.f. A(x) satisfies: A(x) = Product_{k>=1} 1/(1 - x^k*A(x))^k.

Terms

a(0) =1a(1) =1a(2) =4a(3) =14a(4) =54a(5) =213a(6) =880a(7) =3724a(8) =16143a(9) =71227a(10) =319067a(11) =1447160a(12) =6633530a(13) =30682425a(14) =143028870a(15) =671293632a(16) =3169572659a(17) =15044993968a(18) =71752624923a(19) =343658572717