a(n) = n^2*(n^5+1)/2.

Terms

a(0) =0a(1) =1a(2) =66a(3) =1098a(4) =8200a(5) =39075a(6) =139986a(7) =411796a(8) =1048608a(9) =2391525a(10) =5000050a(11) =9743646a(12) =17915976a(13) =31374343a(14) =52706850a(15) =85429800a(16) =134217856a(17) =205169481a(18) =306110178a(19) =446936050a(20) =640000200a(21) =900544491a(22) =1247179186a(23) =1702412988a(24) =2293236000