Largest prime factor of 7^n - 3^n.
2, 5, 79, 29, 101, 79, 205339, 73, 1171, 101, 5553791, 157, 424997, 205339, 4831, 25537, 89888093063, 5743, 2849723505777919, 4871281, 205339, 8597843, 16654666834177, 5576881, 80962848274370701, 9689060473, 447381523, 205339, 12741092841523, 10891
1
T. D. Noe, Plot of 100 terms
T. D. Noe, Table of 100 terms
Eric W. Weisstein, MathWorld: Greatest Prime Factor
(Mma) Table[FactorInteger[7^n - 3^n][[-1, 1]], {n, 40}]
nonn
T. D. Noe, Jun 08 2015