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Old 2019-06-26, 13:37   #13
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Sep 2003

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Originally Posted by mathwiz View Post
What program was used to find factors of W(W(61)) onward?
Originally Posted by GP2 View Post
All Wagstaff factors are 2*k*p + 1 for some k, just like with Mersenne. And k is small enough for those factors that you could quickly find them even with a dumb Python script.
The Double Mersenne Prime Search uses a program called mmff.exe, which is derived from mfaktc.exe

As you mentioned, with mfaktc.exe it suffices to set the -DWAGSTAFF flag to make it find Wagstaff factors instead of Mersenne factors. So maybe that will work with mmff.exe as well, and it might be possible to find a large-ish factor for W(W(43)).

Edit: from looking at the source code, it's not that simple.

Last fiddled with by GP2 on 2019-06-26 at 14:14
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