Largest n-digit prime.

Terms

a(0) =7a(1) =97a(2) =997a(3) =9973a(4) =99991a(5) =999983a(6) =9999991a(7) =99999989a(8) =999999937a(9) =9999999967a(10) =99999999977a(11) =999999999989