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Old 2022-06-18, 20:01   #1
mikedons
 
Nov 2021

2 Posts
Default Question on "ECM on Mersenne cofactor" work type

I set Prime95 up to do the "ECM on Mersenne cofactor" work type and was sort of expecting that I would get an assignment that ran ECM on a cofactor of a Mersenne number many times, until it was deemed unproductive to continue. What actually happens is that I get an assignment to do ECM on a Mersenne number once, then it moves on to a different Mersenne number.

Using M2106347 as an example (approx 700000 decimal digits if my maths is correct), it has 4 known factors totalling about 50 decimal digits, so the remaining unfactored amount is relatively speaking a similar size to M2106347. Is this why we just repeat the ECM on M2106347 instead of on the unfactored amount?

I still don't understand the apparent scatter gun approach where I get assigned 1 attempt at many different exponents (rather than repeatedly trying to factor the same number).
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