a(n) = 2^n-n^11.

Terms

a(0) =1a(1) =1a(2) =-2044a(3) =-177139a(4) =-4194288a(5) =-48828093a(6) =-362796992a(7) =-1977326615a(8) =-8589934336a(9) =-31381059097a(10) =-99999998976a(11) =-285311668563a(12) =-743008366592