G.f.: Product_{k>=1} Sum_{n>=0} x^(k*n) / (1 - x^(n+k)).

Terms

a(0) =1a(1) =2a(2) =4a(3) =9a(4) =14a(5) =29a(6) =44a(7) =77a(8) =120a(9) =195a(10) =291a(11) =453a(12) =673a(13) =998a(14) =1460a(15) =2101a(16) =3034a(17) =4287a(18) =6051a(19) =8430a(20) =11766a(21) =16098a(22) =22209a(23) =30078a(24) =40881a(25) =54914a(26) =73814a(27) =98159a(28) =130804a(29) =172507