a(n) = 10^(2n+1) - 1 - 3*10^n.

A332196

a(n) = 10^(2n+1) - 1 - 3*10^n.

Terms

    a(0) =6a(1) =969a(2) =99699a(3) =9996999a(4) =999969999a(5) =99999699999

External references