a(n) = n^2*(n^7+1)/2.

Terms

a(0) =0a(1) =1a(2) =258a(3) =9846a(4) =131080a(5) =976575a(6) =5038866a(7) =20176828a(8) =67108896a(9) =193710285a(10) =500000050a(11) =1178973906a(12) =2579890248a(13) =5302249771a(14) =10330523490a(15) =19221679800a(16) =34359738496a(17) =59293938393a(18) =99179645346a(19) =161343849070a(20) =256000000200a(21) =397140023511a(22) =603634609138a(23) =900576330996