a(n) = 6*10^n + 1.

Terms

a(0) =7a(1) =61a(2) =601a(3) =6001a(4) =60001a(5) =600001a(6) =6000001a(7) =60000001a(8) =600000001a(9) =6000000001a(10) =60000000001a(11) =600000000001