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

Terms

a(0) =1a(1) =8a(2) =177a(3) =2530a(4) =18785a(5) =94932a(6) =397585a(7) =1647086a(8) =7861953a(9) =45136576a(10) =292475249a(11) =1996813914a(12) =13877119009a(13) =96951758924a(14) =678328486353