a(n) = 10^(2n+1) - 1 - 2*10^n.A332197a(n) = 10^(2n+1) - 1 - 2*10^n.Terms a(0) =7a(1) =979a(2) =99799a(3) =9997999a(4) =999979999a(5) =99999799999External referencesoeis: A332197