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Old 2019-01-12, 01:21   #266
philmoore's Avatar
Sep 2002
Tracktown, U.S.A.

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I found the larger of the two known prime factors of M8191 in 2003 and did the computations at the time to show that the cofactor was not only composite, but was also not a power of a single prime factor, so we know that the cofactor has at least two distinct prime factors. Currently, the ECM status shows that it probably has no other factors less than around 50 digits.
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