a(n) = 2^n-n^8.

Terms

a(0) =1a(1) =1a(2) =-252a(3) =-6553a(4) =-65520a(5) =-390593a(6) =-1679552a(7) =-5764673a(8) =-16776960a(9) =-43046209a(10) =-99998976a(11) =-214356833a(12) =-429977600a(13) =-815722529a(14) =-1475772672a(15) =-2562857857a(16) =-4294901760a(17) =-6975626369a(18) =-11019698432a(19) =-16983038753a(20) =-25598951424