a(n) = n*(n+1)*(2*n^3 - n^2 + 2)^2/6.

Terms

a(0) =0a(1) =3a(2) =196a(3) =4418a(4) =43320a(5) =257645a(6) =1108828a(7) =3810996a(8) =11105328a(9) =28524615a(10) =66322740a(11) =142270678a(12) =285547496a(13) =541981713a(14) =980925260a(15) =1704069160a(16) =2856536928a(17) =4640618571a(18) =7332534948a(19) =11302649130a(20) =17039568280a(21) =25178606453a(22) =36535105596a(23) =52143138908a(24) =73300147600