G.f.: x * Product_{j>=1, k>=1} (1 + a(j)*x^(j*k)).

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =11a(5) =26a(6) =64a(7) =159a(8) =397a(9) =1042a(10) =2701a(11) =7249a(12) =19341a(13) =52927a(14) =143615a(15) =399359a(16) =1099846a(17) =3087498a(18) =8616361a(19) =24386458a(20) =68617936a(21) =195678409a(22) =554862501a(23) =1590363317a(24) =4539073167a(25) =13071768304a(26) =37496646028a(27) =108449257539a(28) =312439316258a(29) =906653694239