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Factor Number too large? #40

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armedtoe opened this issue May 26, 2016 · 2 comments
Open

Factor Number too large? #40

armedtoe opened this issue May 26, 2016 · 2 comments

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@armedtoe
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armedtoe commented May 26, 2016

I pulled this as the key:
8811106517749122387396306544400207294871116053309887778576518664178301264939320656920208097906596791502301012940291279838618778984913079372866311136903184

Which factors out at 2 · 2 · 2 · 2 · 23 · 457 · 463 · 2729 · 23764707731 · 1744815170161051248900308994924756256109406768546917854295618000464153623295035355691181383026704200051673336306676896452424627447107

The last number is too large, and I get the error "Factor no9 too large!."

Is there a workaround? Thankfully the number was on FactorDB so I didn't have to factor those manually.

Thanks,
Armedtoe

@Demonslay335
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Demonslay335 commented May 27, 2016

The number is listed as CF, which means it has a composite. The last C number still needs factored. I have run ECM on it and obtained one more factor (submitted), but there is still a C120 that remains. I'm afraid I do not have a CPU open for factoring this (i7 with 8 cores, would expect it to take about 24-36 hours).

If you have a good system available, I would use this command to force the composite into NFS, since I've already confirmed ECM won't get any more factors (shave a few hours off your work).

yafu-x64 factor(534632368639489905957918437187520865610866748160803450641401678002571033938915811919018412187387746852856877942298450131) -v -threads 8 -plan noecm -work 40

Change the number of threads accordingly of course. You will get an ETA eventually out of it once it has finished the polynomial selection (ton of numbers scrolling by rapidly), and done a few algebraic sieving rounds. Do not believe the first ETA you see, it will be astronomical; let it get another round and only believe the next ETA that should be a bit more reasonable.

@aurelioig
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I had the same issue.....

I factored the last big number with this command:

"msieve152 -v 1570095799816283656164654922360674046933831856109324388693746179575598389274151985006233276325444708021896561536837257"

It took 5 days with an i7 machine.

I posted the results to factordb.

I had successfully recovering the files (.ccc) !!! Awsome!!!

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