G.f. satisfies: A(x) = Sum_{n>=0} x^n * Product_{d|n} A(x^d)^(n/d).

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =15a(5) =45a(6) =147a(7) =484a(8) =1649a(9) =5698a(10) =20055a(11) =71373a(12) =256998a(13) =933458a(14) =3418160a(15) =12601291a(16) =46739440a(17) =174281272a(18) =652962532a(19) =2456802244a(20) =9279423954a(21) =35170693226a(22) =133726116806a(23) =509926989456