a(n) = (1/48)*n*(n+5)^2*(1*n^3 + 7*n^2 + 16*n + 28).

Terms

a(0) =0a(1) =39a(2) =196a(3) =664a(4) =1809a(5) =4250a(6) =8954a(7) =17346a(8) =31434a(9) =53949a(10) =88500a(11) =139744a(12) =213571a(13) =317304a(14) =459914a(15) =652250a(16) =907284a(17) =1240371a(18) =1669524a(19) =2215704a(20) =2903125a(21) =3759574a(22) =4816746a(23) =6110594a(24) =7681694a(25) =9575625a(26) =11843364a(27) =14541696a(28) =17733639a(29) =21488884