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16843Re: Prime95, glitch or reality?

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  • Phil Carmody
    Jul 4, 2005
      From: "j_m_berg" <j_m_berg@...>
      >
      > I've been running Prime95 with a smaller B1/B2 and a huge exponent
      > (M33554432).
      >
      > I realized this morning that the box has been stuck on the same curve
      > for the last 18 hours, when it normally finishes a curve in 2 hours.
      > So I checked the Prime95 folder and found a results.txt file with the
      > following entry.
      >
      > - - -
      > [Sat Jul 02 16:05:36 2005]
      > ECM found a factor in curve #11, stage #1
      > Sigma=4573583067221178, B1=2000, B2=200000.

      With a B1 that low, it's quite likely that the factor, if it really exists,
      could be found with only trial division.

      For each prime p of the form k*33554432+1, find 2^33554432 (mod p). If it's
      one, that's a factor. That calculation is only 20 modular squarings (of 2^32),
      and it should be trivial to hammer out 10^10 of those in no time at all.

      Paul/David/Jim - you're the fast x86 guys - can you be of any help?

      Phil


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