a(n) = 11*10^n + 1.

Terms

a(0) =12a(1) =111a(2) =1101a(3) =11001a(4) =110001a(5) =1100001a(6) =11000001a(7) =110000001a(8) =1100000001a(9) =11000000001a(10) =110000000001