a(n) = n^2*(n+1)*(4*n^3 - 2*n^2 + n + 3)/12.

Terms

a(0) =0a(1) =1a(2) =29a(3) =288a(4) =1540a(5) =5725a(6) =16821a(7) =41944a(8) =92688a(9) =186705a(10) =349525a(11) =616616a(12) =1035684a(13) =1669213a(14) =2597245a(15) =3920400a(16) =5763136a(17) =8277249a(18) =11645613a(19) =16086160a(20) =21856100a(21) =29256381a(22) =38636389a(23) =50398888a(24) =65005200a(25) =82980625a(26) =104920101a(27) =131494104a(28) =163454788a(29) =201642365