G.f. satisfies A(x) = Product_{k>0} (1+x^k*A(x)).

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =12a(5) =30a(6) =77a(7) =201a(8) =532a(9) =1427a(10) =3868a(11) =10579a(12) =29161a(13) =80931a(14) =225954a(15) =634197a(16) =1788453a(17) =5064877a(18) =14398536a(19) =41074364a(20) =117541744a(21) =337337862a(22) =970704394a(23) =2800059428a(24) =8095161902a(25) =23452565124a(26) =68076579332a(27) =197965830430