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

Terms

a(0) =1a(1) =4a(2) =3a(3) =10a(4) =8a(5) =18a(6) =7a(7) =40a(8) =9a(9) =44a(10) =41a(11) =54a(12) =13a(13) =150a(14) =15a(15) =88a(16) =127a(17) =168a(18) =19a(19) =298a(20) =21a(21) =324a(22) =275a(23) =180a(24) =25a(25) =854a(26) =132a(27) =238a(28) =524a(29) =774