a(n) = 2^n - n^7.

Terms

a(0) =1a(1) =1a(2) =-124a(3) =-2179a(4) =-16368a(5) =-78093a(6) =-279872a(7) =-823415a(8) =-2096896a(9) =-4782457a(10) =-9998976a(11) =-19485123a(12) =-35827712a(13) =-62740325a(14) =-105397120a(15) =-170826607a(16) =-268369920a(17) =-410207601a(18) =-611957888a(19) =-893347451a(20) =-1278951424a(21) =-1798991389a(22) =-2490163584a(23) =-3396436839