Largest prime factor of 8^n - 7^n.
1, 5, 13, 113, 1451, 19, 1273609, 113, 2791, 1451, 6612607849, 3361, 866477, 1273609, 2011, 1326001, 2019169299698041, 68059, 15792314893, 12001921, 1273609, 6612607849, 2196464096219, 12707521, 120998384851, 43109654953, 92468566625599, 5512669
1
We include the first term even though it is not prime. The n that produce prime 8^n - 7^n are in A062574.
T. D. Noe, Plot of 100 terms
T. D. Noe, Table of 100 terms
Eric W. Weisstein, MathWorld: Greatest Prime Factor
(Mma) Table[FactorInteger[8^n - 7^n][[-1, 1]], {n, 40}]
nonn
T. D. Noe, Jun 08 2015