G.f.: (1 + x) * (1 + x^2) * (1 + x^3) * Product_{k>=1} (1 + x^k).

Terms

a(0) =1a(1) =2a(2) =3a(3) =6a(4) =8a(5) =11a(6) =16a(7) =20a(8) =26a(9) =34a(10) =43a(11) =54a(12) =68a(13) =84a(14) =103a(15) =127a(16) =154a(17) =186a(18) =225a(19) =269a(20) =321a(21) =383a(22) =453a(23) =535a(24) =631a(25) =740a(26) =866a(27) =1012a(28) =1178a(29) =1368