WinPFGW 3.6.5:
2^401215-1657 is 3-PRP! (85.2388s+0.0001s)
2^417095-1657 is 3-PRP! (91.7257s+0.0008s)
2^488280-2165 is 3-PRP! (137.0496s+0.0010s)

To be completed...