n 1's followed by three 0's.

A161770

n 1's followed by three 0's.

Terms

    a(0) =1000a(1) =11000a(2) =111000a(3) =1111000a(4) =11111000a(5) =111111000a(6) =1111111000a(7) =11111111000a(8) =111111111000

External references