a(n) = 8^n - n^11.

Terms

a(0) =1a(1) =7a(2) =-1984a(3) =-176635a(4) =-4190208a(5) =-48795357a(6) =-362534912a(7) =-1975229591a(8) =-8573157376a(9) =-31246841881a(10) =-98926258176a(11) =-276721736019a(12) =-674288893952a(14) =348481341440