Expansion of g.f.: (1+x)/(1-10*x).

Terms

a(0) =1a(1) =11a(2) =110a(3) =1100a(4) =11000a(5) =110000a(6) =1100000a(7) =11000000a(8) =110000000a(9) =1100000000a(10) =11000000000a(11) =110000000000