G.f.: Sum_{n>=1} x^n / (1-x)^prime(n).

Terms

a(0) =1a(1) =3a(2) =7a(3) =16a(4) =38a(5) =96a(6) =262a(7) =767a(8) =2346a(9) =7315a(10) =22954a(11) =72239a(12) =228484a(13) =730470a(14) =2379669a(15) =7960733a(16) =27453387a(17) =97418566a(18) =353442491a(19) =1300699953a(20) =4821108695a(21) =17903653177a(22) =66375491706a(23) =245111697148a(24) =900578294735