a(n) = 10^(2*n+1) - 1 - 7*10^n.

A332192

a(n) = 10^(2*n+1) - 1 - 7*10^n.

Terms

    a(0) =2a(1) =929a(2) =99299a(3) =9992999a(4) =999929999a(5) =99999299999

External references