a(n) = n^8*(n^2+1)/2.

Terms

a(0) =0a(1) =1a(2) =640a(3) =32805a(4) =557056a(5) =5078125a(6) =31072896a(7) =144120025a(8) =545259520a(9) =1764915561a(10) =5050000000a(11) =13075891741a(12) =31173672960a(13) =69337111285a(14) =145365222016a(15) =289606640625a(16) =551903297536