This is from Aliquot sequence 363270:i1731 c157:[code]Tue Jul 12 07:15:33 2011 prp77 factor: 10627165781862247141424434491952385141030569384792474376105958229098506812363
Tue Jul 12 07:15:33 2011 prp81 factor: 218154811813343763045096879451444238851523980088473271264335835306807710584492227
Tue Jul 12 07:15:33 2011 elapsed time 126:53:00[/code]After ~6 weeks of sieving....:whew:!

small feat for a small computer
 

Input number is Phi(1302,10)/1303/10439437 (350 digits) (cofactor of 10^651+1)
Using B1=43000000, B2=240490660426, polynomial Dickson(12), sigma=4183461552
Step 1 took 388800ms
Step 2 took 89448ms
********** Factor found in step 2: 25540795299896197421506059449931706821324283570117
Found probable prime factor of 50 digits: 25540795299896197421506059449931706821324283570117
Probable prime cofactor has 301 digits

[QUOTE=schickel;266470]This is from Aliquot sequence 363270:i1731 c157:[code]Tue Jul 12 07:15:33 2011 prp77 factor: 10627165781862247141424434491952385141030569384792474376105958229098506812363
Tue Jul 12 07:15:33 2011 prp81 factor: 218154811813343763045096879451444238851523980088473271264335835306807710584492227
Tue Jul 12 07:15:33 2011 elapsed time 126:53:00[/code]After ~6 weeks of sieving....:whew:![/QUOTE]

1. And by what means was this factor "gratuitous"? :P:P
2. How big the nfs.dat got? I am thinking with fear for my C185, which already reached 3 gigs... How much longer it will go? Does the program gets slower as the file size increase? (operating large files slows the things a lot in windoze). etc..

Is your C185 being factored by SNFS or GNFS, LaurV ?

@debrouxl: see [URL="http://www.mersenneforum.org/showpost.php?p=269861&postcount=1196"]here [/URL]and [URL="http://www.mersenneforum.org/showpost.php?p=269817&postcount=813"]here[/URL] the long arguing phase :D (click on the "thread" buttons on the upper right corners, I don't know how to put a link to show whole thread when is clicked). I am following fivemack's advices, yafu nfs, lasieve4I14e, about 24 million relations already. No idea where and when it will stop. If I started, I want to finish it, and as bsqared said there, let this be a lesson... :P

What fivemack posted is a poly for a 29-bit large primes sieving. For such sievings, I always make RSALS generate ~60M raw relations (which represent a variable amount of oversieving, depending on the difficulty of the factorization), and the relations end up being ~3.5e9 bytes gzipped, i.e. ~7-7.5e9 bytes uncompressed. So I [I]think[/I] that you have, more or less, half of the relations you need. I'll let other give more precise measurements :smile:

[QUOTE=LaurV;273350]1. And by what means was this factor "gratuitous"? :P:P[/quote]Gratuitous in that it had no particular meaning.....other than it was my biggest solo factoring job (so far!)[quote]2. How big the nfs.dat got? I am thinking with fear for my C185, which already reached 3 gigs... How much longer it will go? Does the program gets slower as the file size increase? (operating large files slows the things a lot in windoze). etc..[/QUOTE]I would have to check and see if I still have the log from that one. Not sure if I kept it.....I don't think it got much bigger than 4-5 GB, while the linear algebra took in the neighborhood of 2GB or so.

As far as a slowdown, you don't have much to worry about with respect to the sieving. The siever(s) just append to the end of the output file(s), while the script just appends all the relations to the main .dat file. The real bottleneck is going to be the filtering: at that point, msieve needs to read the entire data set into memory, so the more RAM you have, the better!

Thanks both of you.

@schickel: didn't know that meaning, checked it with the dic. :D formerly, I assumed the "for free" meaning, like you try to do some job and in the process you get something like a side effect. Ex: "using real fft to square the LL residues gives the mod step for free". So, it was a bit strange to post in a "gratuitous factors" thread some factor for which you, in fact, worked a lot (6 weeks of sieving!)..

Now is more clear (and the meaning of the thread is more clear too). If I find a billion digit prime which is gratuitous, I will post it here. :smile:

I think this is somewhat rare
 

2 P-1 factors found
Same PC
Within less than 10 hours
Exponents less than 400 apart

54124061 F-PM1 2011-10-14 20:23 18.2 352159225282492980943033
54124429 F-PM1 2011-10-14 10:28 17.7 30040116253778302437391

By matsui: [URL="http://factordb.com/index.php?id=1100000000002982874"]a p99*p99 split[/URL]

[SIZE=1](previous largest p97*p97 [/SIZE][URL="http://homepage2.nifty.com/m_kamada/math/records.htm#nicesplit"][SIZE=1]"nice split" for near-repunit[/SIZE][/URL][SIZE=1] was also by the same person)[/SIZE]

I've just found my first Mersenne P-1 factor (IIRC), discovered as part of GPU to 72. :smile: It's 76 bits (~2^75.22, or 23 digits) and with k=83*9029*15359*40433 just fit into the stage 1 bounds.
[CODE]P-1 found a factor in stage #1, B1=445000.
M47403971 has a factor: 44122627934020297446119[/CODE]Curiously, GPU to 72 credited me 3.020 GHz-days, though PrimeNet gave me 1.1202 GHz-days (a result which mersenne-aries [URL="http://mersenne-aries.sili.net/credit.php?worktype=P-1&exponent=47403971&f_exponent=&b1=445000&b2=445000&numcurves=&factor=44122627934020297446119&frombits=&tobits=&submitbutton=Calculate"]agrees on[/URL]). Does GPU to 72 lack the information for properly crediting factors, or do they use different criteria?