L.g.f.: Sum_{n>=1} (x^n/n) * Product_{d|n} (1 + d*x^n).

Terms

a(0) =1a(1) =3a(2) =1a(3) =7a(4) =1a(5) =15a(6) =1a(7) =15a(8) =10a(9) =13a(10) =1a(11) =67a(12) =1a(13) =17a(14) =16a(15) =63a(16) =1a(17) =168a(18) =1a(19) =37a(20) =22a(21) =25a(22) =1a(23) =555a(24) =1a(25) =29a(26) =118a(27) =49a(28) =1a(29) =520