Largest prime factor of 5^n - 4^n.
1, 3, 61, 41, 191, 61, 2129, 881, 1459, 461, 7019, 61, 14602459, 10501, 7411, 26833, 248779, 3907, 22639679, 263761, 594511, 256147, 6031199, 4057, 3818201, 14602459, 94425589, 120569, 1482830563601, 362581, 108897707976754259, 32677121, 42730786509181
1
We include the first term even though it is not prime. The n that produce prime 5^n - 4^n are in A059802.
T. D. Noe, Plot of 100 terms
T. D. Noe, Table of 100 terms
Eric W. Weisstein, MathWorld: Greatest Prime Factor
(Mma) Table[FactorInteger[5^n - 4^n][[-1, 1]], {n, 40}]
nonn
T. D. Noe, Jun 08 2015