a(n) = (8*10^(2n) - 10^(n+1) + 2) / 9.

A383942

a(n) = (8*10^(2n) - 10^(n+1) + 2) / 9.

Terms

    a(0) =78a(1) =8778a(2) =887778a(3) =88877778a(4) =8888777778a(5) =888887777778

External references