a(0)=0; a(n) = 10*a(n-1) + 10.

Terms

a(0) =0a(1) =10a(2) =110a(3) =1110a(4) =11110a(5) =111110a(6) =1111110a(7) =11111110a(8) =111111110a(9) =1111111110a(10) =11111111110a(11) =111111111110