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

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =5a(5) =8a(6) =12a(7) =20a(8) =28a(9) =45a(10) =65a(11) =101a(12) =148a(13) =221a(14) =316a(15) =469a(16) =673a(17) =969a(18) =1420a(19) =2025a(20) =2892a(21) =4100a(22) =5905a(23) =8314a(24) =11860a(25) =16645a(26) =23399a(27) =32838a(28) =46071a(29) =64274