a(n) = (n-1)*(n+2)*(n^2 + n + 2)/4.

Terms

a(0) =0a(1) =8a(2) =35a(3) =99a(4) =224a(5) =440a(6) =783a(7) =1295a(8) =2024a(9) =3024a(10) =4355a(11) =6083a(12) =8280a(13) =11024a(14) =14399a(15) =18495a(16) =23408a(17) =29240a(18) =36099a(19) =44099a(20) =53360a(21) =64008a(22) =76175a(23) =89999a(24) =105624a(25) =123200a(26) =142883a(27) =164835a(28) =189224a(29) =216224