PRP in base 79 and 83

For (27^n-25^n)/2, I found hitherto:
(27^3-25^3)/2
(27^17-25^17)/2
(27^61-25^61)/2
(27^2777-25^2777)/2
(27^18211-25^18211)/2=(3^54633-5^36422)/2

To be completed...