WinPFGW 3.7.10:
2^526658-3551 is 3-PRP! (164.0130s+0.0007s)
2^477359-3577 is 3-PRP! (136.9634s+0.0007s)
2^542072-3683 is 3-PRP! (194.3160s+0.0008s)
2^584671-3697 is 3-PRP! (209.5762s+0.0007s)

To be completed...