fond of a factor? Urn yourself to become remains

[Dubslow]

Originally Posted by flashjh

P-1 found a factor in stage #1, B1=535000.
M57185879 has a factor: 252575061844706872759614361 (27 digits, 87.707 bits)
k = 2208369148655622420
2² × 3 × 5 × 13² × 19 × 149 × 1621 × 4871 × 9743

Lol, what a lot of wasted CPU time

[firejuggler]

http://mersenne-aries.sili.net/expon...27452892424807
[Fri Aug 24 07:06:46 2012]
P-1 found a factor in stage #1, B1=95000.
UID: firejuggler, M8381311 has a factor: 131857961859014427452892424807 (96.735 bit)

k=3^2 × 11 × 132 × 157 × 653 × 8971 × 11971 × 42703

that's really strange, because a P-1 with B1=35k and B2=271250 was done before

[ckdo]

Originally Posted by firejuggler

that's really strange, because a P-1 with B1=35k and B2=271250 was done before

B2/B1=7.75 looks odd enough.

[firejuggler]

can we suppose that such strange ratio are in fact, only B1 done?

[c10ck3r]

M998423 has a factor: 335121480072681895178941249
k=2^5*3^2*485201*535349*2243399
Found stage 1, with P-1 bounds B1=2,500,000 b2=50,000,000.

[aketilander]

[Sat Aug 25 14:19:11 2012]
UID: aketilander/OBD, M3321932491 has a factor: 28126803354429776910329417 [TF:84:85:mfaktc 0.19 barrett92_mul32]

84.540 bits

k=4233500143460588
(2 x 2 × 7 × 11 × 13 × 17 × 128837 × 482743)

My first factor in the project Operation Billion Digits.

This is to the best of my knowledge the largest non composite factor found for Mersenne prime exponents less then 2^32 (4294967296) using ordinary trial factoring, see http://www.mersenne-aries.sili.net/s...howuserstats=*

[firejuggler]

congratz aketilander. That"s a very large one. How long did it take?

[aketilander]

Originally Posted by firejuggler

congratz aketilander. That"s a very large one. How long did it take?

Well, I started trial factoring M3321932491 on August 12 (at 22:20 local time here) from ^82 to ^86. The expo had finished the first two bits on August 24 (15:27 local time) and started factoring from ^84 to ^85. The factor was found on August 25 at 14:19. Presently only 15.8% of the interval ^84 to ^85 is finished so the factor was found very early in this interval.

To completely trial factoring this expo from ^84 to ^85 will probably take around 14 days on that card.

I may have lost an hour or so upgrading from Mfaktc 0.18 to 0.19 before beginning trial factoring from ^84.

I continue trial factoring M3321932491 up to ^86 as planned from the beginning.

[ET_]

Originally Posted by aketilander

[Sat Aug 25 14:19:11 2012]
UID: aketilander/OBD, M3321932491 has a factor: 28126803354429776910329417 [TF:84:85:mfaktc 0.19 barrett92_mul32]

84.540 bits

k=4233500143460588
(2 x 2 × 7 × 11 × 13 × 17 × 128837 × 482743)

My first factor in the project Operation Billion Digits.

This is to the best of my knowledge the largest non composite factor found for Mersenne prime exponents less then 2^32 (4294967296) using ordinary trial factoring, see http://www.mersenne-aries.sili.net/s...howuserstats=*

[ixfd64]

Originally Posted by Jwb52z

Why was this thread renamed?

Mike's gerbils probably got lose or something.

[Axelsson]

Found some factors by TF that P-1 and ECM missed.

M1129153 has a factor: 4059448173685700567 [TF:61:62*:mfakto 0.13pre1-Win barrett15_75]

k=110917 · 16206383

1129153 No factors below 2^61
P-1 B1=100000, B2=2000000
History 1 curves, B1=50000, B2=5000000 by "Chad Davis" on 2007-10-06
History 3 curves, B1=50000, B2=5000000 by "Sturle Sunde" on 2008-05-18
History 3 curves, B1=50000, B2=5000000 by "bayanne" on 2008-12-18
History no factor from 2^60 to 2^61 by "Sturle Sunde" on 2009-02-18
History 3 curves, B1=50000, B2=5000000 by "Lukasz Wrobel" on 2009-05-30
History 3 curves, B1=50000, B2=5000000 by "Lupo" on 2009-09-06
History 3 curves, B1=50000, B2=5000000 by "Lupo" on 2009-12-23
History 3 curves, B1=50000, B2=5000000 by "Charles A. Morris" on 2010-06-14
History 3 curves, B1=50000, B2=5000000 by "unconnected" on 2011-01-30
History 3 curves, B1=50000, B2=5000000 by "Andriy Makukha" on 2011-11-01
History 3 curves, B1=50000, B2=5000000 by "Lackó" on 2012-07-13

I know that the reason p-1 missed this one is that no factors of k is less than B1 and the second factor is bigger than B2 (not B2 powersmooth).
Is that the reason ECM couldn't find it either?

M1143719 has a factor: 2479139950847214497 [TF:61:62*:mfakto 0.13pre1-Win barrett15_75]

k=2^4 · 41 · 1652143907

1143719 No factors below 2^61
P-1 B1=500000, B2=10000000
History 1 curves, B1=50000, B2=5000000 by "James Heinrich" on 2007-10-08
History 3 curves, B1=50000, B2=5000000 by "James Heinrich" on 2008-06-05
History 3 curves, B1=50000, B2=5000000 by "Sturle Sunde" on 2008-12-29
History no factor from 2^60 to 2^61 by "Sturle Sunde" on 2009-02-15
History 3 curves, B1=50000, B2=5000000 by "Geoff Wing" on 2009-06-01
History 3 curves, B1=50000, B2=5000000 by "Geoff Wing" on 2009-09-10
History 3 curves, B1=50000, B2=5000000 by "sannerud.com" on 2009-12-31
History 3 curves, B1=50000, B2=5000000 by "Charles A. Morris" on 2010-06-23
History 3 curves, B1=50000, B2=5000000 by "greensinoz" on 2011-02-12
History 3 curves, B1=50000, B2=5000000 by "Andriy Makukha" on 2011-11-06
History B1=500000, B2=10000000 by "markr" on 2012-01-31
History 3 curves, B1=50000, B2=5000000 by "soldake" on 2012-07-16

This one I have a harder time to understand.... oh, stupid of me, the last factor is bigger than B2 for P-1, didn't see that at first. This isn't smooth compared to B2 either. I think I'm getting a grip of the p-1 method now.

You learn something new every day.

But I can't see a reason to why ECM didn't find the factors. Is that just bad luck or does the composition of the factor have something to do with it?
I'm trying to understand how the different factorisation algorithms works or when it fails.

/Göran