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

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =10a(5) =22a(6) =57a(7) =134a(8) =331a(9) =797a(10) =1995a(11) =4879a(12) =12367a(13) =31056a(14) =79315a(15) =202370a(16) =521575a(17) =1339934a(18) =3456778a(19) =8885907a(20) =22848211a(21) =58576714a(22) =150117209a(23) =384135566a(24) =983789032a(25) =2522109065a(26) =6485104365a(27) =16736092434a(28) =43408268497a(29) =113201300205