a(n) = 11*8^n+1.

Terms

a(0) =12a(1) =89a(2) =705a(3) =5633a(4) =45057a(5) =360449a(6) =2883585a(7) =23068673a(8) =184549377a(9) =1476395009a(10) =11811160065a(11) =94489280513a(12) =755914244097