a(n) = (n^6 - 30*n^4 + 45*n^3 + 206*n^2 - 576*n + 384)/6.

Terms

a(0) =0a(1) =4a(2) =112a(3) =859a(4) =3640a(5) =11250a(6) =28544a(7) =63217a(8) =126704a(9) =235200a(10) =410800a(11) =682759a(12) =1088872a(13) =1676974a(14) =2506560a(15) =3650525a(16) =5197024a(17) =7251452a(18) =9938544a(19) =13404595a(20) =17819800a(21) =23380714a(22) =30312832a(23) =38873289a(24) =49353680a(25) =62083000a(26) =77430704a(27) =95809887a(28) =117680584a(29) =143553190