a(n) = 7*9^n + 1.

Terms

a(0) =8a(1) =64a(2) =568a(3) =5104a(4) =45928a(5) =413344a(6) =3720088a(7) =33480784a(8) =301327048a(9) =2711943424a(10) =24407490808a(11) =219667417264