a(n) = 11^n-5^n+1.

Terms

a(0) =1a(1) =7a(2) =97a(3) =1207a(4) =14017a(5) =157927a(6) =1755937a(7) =19409047a(8) =213968257a(9) =2355994567a(10) =25927658977a(11) =285262842487