Sum_{k=1..n, gcd(n,k) = 1} 10^(k-1).

Terms

a(0) =1a(1) =11a(2) =101a(3) =1111a(4) =10001a(5) =111111a(6) =1010101a(7) =11011011a(8) =101000101a(9) =1111111111a(10) =10001010001a(11) =111111111111