PFGW 3.6.5:
2^462238-935 is 3-PRP! (298.5578s+0.0020s)
2^501627-991 is 3-PRP! (388.4666s+0.0021s)
2^447552-1019 is 3-PRP! (288.8773s+0.0020s)

To be completed...