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Old 2020-01-24, 23:41   #295
JeppeSN's Avatar
Jan 2016

2·71 Posts

It is the same Scott Brown who found another Fermat factor, 9*2^2543551+1, back in 2011, in a similar way.

In PrimeGrid, the participants detect the primality (two persons do it concurrently, the one finishing first is declared the finder). Whether the new Proth prime divides any Fermat number (and/or generalized Fermat numbers with bases at most 12) is detected by PrimeGrid's server, not the participant's computer.

The link posted by ATH shows the timing (primality was reported "22 Jan 2020 | 15:00:58 UTC") and some hardware ("Intel(R) Core(TM) i7-4790 CPU @ 3.60GHz [Family 6 Model 60 Stepping 3]").

The other participant was Stefan Larsson (returned "22 Jan 2020 | 15:11:39 UTC").

At some point PrimeGrid will publish an official announcement (PDF).

This was PrimeGrid's first Fermat divisor in five years. They recently introduced a new subproject that focuses on Proth primes with low "k" (the odd multiplier) because that gives higher probability of Fermat divisors. This approach was recommended by Ravi Fernando and others.

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