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

Terms

a(0) =0a(1) =1a(2) =257a(3) =9843a(4) =131074a(5) =976565a(6) =5038851a(7) =20176807a(8) =67108868a(9) =193710249a(10) =500000005a(11) =1178973851a(12) =2579890182a(13) =5302249693a(14) =10330523399a(15) =19221679695a(16) =34359738376a(17) =59293938257a(18) =99179645193a(19) =161343848899a(20) =256000000010a(21) =397140023301a(22) =603634608907