Largest prime factor of 10^n - 1.

Terms

a(0) =3a(1) =11a(2) =37a(3) =101a(4) =271a(5) =37a(6) =4649a(7) =137a(8) =333667a(9) =9091a(10) =513239a(11) =9901a(12) =265371653a(13) =909091a(14) =2906161a(15) =5882353a(16) =5363222357a(17) =333667a(19) =27961a(20) =10838689a(21) =513239a(23) =99990001a(24) =182521213001a(25) =1058313049