PRP in base 79 and 83

For (41^n-39^n)/2, I found hitherto:
(41^3-39^3)/2
(41^17-39^17)/2
(41^347-39^347)/2
(41^1427-39^1427)/2
(41^1759-39^1759)/2
(41^8039-39^8039)/2

To be completed...