a(n) = (16*10^n - 7)/9.

A246058

a(n) = (16*10^n - 7)/9.

Terms

    a(0) =1a(1) =17a(2) =177a(3) =1777a(4) =17777a(5) =177777a(6) =1777777a(7) =17777777a(8) =177777777a(9) =1777777777a(10) =17777777777a(11) =177777777777

External references