a(n) = (n - 1)*n*(2*n^2 + 4*n - 1)/6.

Terms

a(0) =0a(1) =0a(2) =5a(3) =29a(4) =94a(5) =230a(6) =475a(7) =875a(8) =1484a(9) =2364a(10) =3585a(11) =5225a(12) =7370a(13) =10114a(14) =13559a(15) =17815a(16) =23000a(17) =29240a(18) =36669a(19) =45429a(20) =55670a(21) =67550a(22) =81235a(23) =96899a(24) =114724a(25) =134900a(26) =157625a(27) =183105a(28) =211554a(29) =243194