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

Terms

a(0) =10a(1) =87a(2) =703a(3) =5631a(4) =45055a(5) =360447a(6) =2883583a(7) =23068671a(8) =184549375a(9) =1476395007a(10) =11811160063a(11) =94489280511a(12) =755914244095