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Old 2009-01-21, 01:34   #6
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"Richard B. Woods"
Aug 2002
Wisconsin USA

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Originally Posted by MatWur-S530113 View Post
to prevent myself from finding of already known factors I need to know them (that's about my second question).
There used to be a regularly-updated file named lowm.txt that listed all known factors. I don't know if it's still maintained somewhere on

Edgington's page has a link to " lowM.txt, DATABASE,, primeM.txt, factoredM.txt, etc., zipped"

I don't know whether its files are updated regularly. If they are, you could get lowm.txt there.

If a number like M2251 is already completely factored, then the project doesn't need anymore list all factors, one is enough. But then at least a hint about the status of completely factored is needed imho. Or you can get such trouble like I got. Of course I know that such an exponent is not longer listet at the ECM-status page for M-numbers with known factors. But I don't look always at the ECM-page. It is simply a question of time.
So, I presume you're not doing ECM on these exponents, since otherwise how would you decide what B1 to use and how many curves to run?

Then one can be sure about the status without looking at the ECM-status page again...
Why is looking at the ECM-status page such a time-burden for you? How often are factorizations being completed in the range of low exponents you are testing?

Download and store a copy of the page every month or so, so you can refer to that copy quickly offline.

Better yet: sign up for one of those free services that will notify you whenever a particular web page changes, so you can re-download only when it changes.

but do you look every time at this tables for all known factors if you only want to run some ECM-curves at an exponent?
Well ... you'll have to look at some table to get all known factors for that exponent, won't you?

How about downloading and storing a copy of Edgington's table (or the file I mentioned above) once a month or so, whenever you do the same for the ECM-status page? Or put it on your page-change-notification service list.

Last fiddled with by cheesehead on 2009-01-21 at 01:57
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