PRP in base 59 and 61

For (85^n-83^n)/2, I found hitherto:
(85^3-83^3)/2
(85^11-83^11)/2
(85^23-83^23)/2
(85^29-83^29)/2
(85^71-83^71)/2
(85^12763-83^12763)/2

To be completed...