WinPFGW 3.6.0: 2^251784-455 is 3-PRP! (77.7781s+0.0001s) 2^264816-455 is 3-PRP! (81.5323s+0.0006s) 2^281500-455 is 3-PRP! (104.9444s+0.0022s)
To be completed...