a(n) = [x^n] Product_{k>=1} ((1 + x^k)/(1 + x^(n*k)))^n.

Terms

a(0) =1a(1) =0a(2) =1a(3) =10a(4) =47a(5) =201a(6) =849a(7) =3578a(8) =15147a(9) =64516a(10) =276268a(11) =1188342a(12) =5130987a(13) =22226036a(14) =96543989a(15) =420368843a(16) =1834203939a(17) =8018057328a(18) =35107961157a(19) =153950675566a(20) =675978772306