G.f. A(x) satisfies: A(x) = x * exp(Sum_{k>=1} (A(x^k) + sigma(k)*x^k)/k).

Terms

a(0) =0a(1) =1a(2) =2a(3) =6a(4) =17a(5) =52a(6) =161a(7) =524a(8) =1739a(9) =5929a(10) =20562a(11) =72471a(12) =258596a(13) =932897a(14) =3395922a(15) =12459900a(16) =46028216a(17) =171056252a(18) =639072199a(19) =2398886256a(20) =9042816457a(21) =34217811625a(22) =129926976921a(23) =494892472911