a(n) = n^7 + 7*n.

Terms

a(0) =0a(1) =8a(2) =142a(3) =2208a(4) =16412a(5) =78160a(6) =279978a(7) =823592a(8) =2097208a(9) =4783032a(10) =10000070a(11) =19487248a(12) =35831892a(13) =62748608a(14) =105413602a(15) =170859480a(16) =268435568a(17) =410338792a(18) =612220158a(19) =893871872a(20) =1280000140a(21) =1801088688a(22) =2494358042