G.f.: Sum_{n>=0} (n+1)*(n+2)*(n+3)/3! * (x + x^n)^n.

Terms

a(0) =1a(1) =8a(2) =10a(3) =40a(4) =45a(5) =116a(6) =84a(7) =320a(8) =165a(9) =520a(10) =496a(11) =868a(12) =455a(13) =2100a(14) =680a(15) =2136a(16) =2264a(17) =3680a(18) =1330a(19) =6920a(20) =1771a(21) =7988a(22) =6920a(23) =8060a(24) =2925a(25) =22732a(26) =4914a(27) =13580a(28) =17365a(29) =26440