a(n) = 16*a(n-1) - a(n-2).

Terms

a(0) =1a(1) =8a(2) =127a(3) =2024a(4) =32257a(5) =514088a(6) =8193151a(7) =130576328a(8) =2081028097a(9) =33165873224a(10) =528572943487