a(n) = (1/2)*(n^4 + 11*n^3 + 53*n^2 + 97*n + 54).

Terms

a(0) =0a(1) =27a(2) =108a(3) =282a(4) =600a(5) =1125a(6) =1932a(7) =3108a(8) =4752a(9) =6975a(10) =9900a(11) =13662a(12) =18408a(13) =24297a(14) =31500a(15) =40200a(16) =50592a(17) =62883a(18) =77292a(19) =94050a(20) =113400a(21) =135597a(22) =160908a(23) =189612a(24) =222000a(25) =258375a(26) =299052a(27) =344358a(28) =394632a(29) =450225