a(n) = 9^n-n^12.

Terms

a(0) =1a(1) =8a(2) =-4015a(3) =-530712a(4) =-16770655a(5) =-244081576a(6) =-2176250895a(7) =-13836504232a(8) =-68676430015a(9) =-282042115992a(10) =-996513215599