a(n) = 10^(2*n+1) - 1 - 5*10^n.A332194a(n) = 10^(2*n+1) - 1 - 5*10^n.Terms a(0) =4a(1) =949a(2) =99499a(3) =9994999a(4) =999949999a(5) =99999499999External referencesoeis: A332194