20141015, 22:22  #23 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
89×113 Posts 
What was pulled out again? The prime cofactor of the algebraic factor (2^69791)/(2^9971), a.k.a. Phi_{7}(2^997)? It's there.
Last fiddled with by Batalov on 20141015 at 22:25 
20141020, 10:45  #24 
Feb 2013
17×29 Posts 
Still getting a C41715 here both from yafux64's "factor" command and also by running the ecm command also with yafux64.
This time having the output to the screen (or monitor) instead of a file. Took a bit of time to get the ============================================= ecm: 0/1 curves on C41715, B1=11K, B2=gmpecm default visible. Last fiddled with by storflyt32 on 20141020 at 10:47 
20141020, 14:02  #25  
"Ben"
Feb 2007
2^{2}×3×311 Posts 
Quote:
I am sorry that yafu does not work on every conceivable input, but the fact remains that it was not designed to work on numbers like this. Why would you insist that yafu is right when every other piece of software that *was* designed for numbers like this disagree with it? 

20150624, 06:41  #26 
Feb 2013
17×29 Posts 
Do not know where to post this.
http://factordb.com/index.php?id=1100000000785525326 Lying at the bottom of my checkfacts.txt file, the number fits into the factorize line in the Factor Database. Just clicking the Factorize button, it first became "U" for unknown. Clicking the button again and I was told it was a PRP3759. This time it apparently was not because of me. Whose responsibility is to update what and where and if a given number turns out to be a quite large one, who should be credited with the find or discovery? Last fiddled with by storflyt32 on 20150624 at 07:30 
20150624, 11:31  #27  
"Victor de Hollander"
Aug 2011
the Netherlands
49B_{16} Posts 
Quote:
On the status page, one core of the 2600k is dedicated to do this: "Checking the smallest number with status unknown <20000 digits" 

20150625, 11:55  #28 
"Frank <^>"
Dec 2004
CDP Janesville
2×1,061 Posts 

20150715, 21:04  #29 
Feb 2013
111101101_{2} Posts 
http://factordb.com/index.php?id=1100000000792308300
The remaining C103 is a very difficult one. Running it using ecm only could possibly work, but would probably take a very long time, depending on the number of curves which are being selected. Most likely the 9704 curves being used by the Yafu software is not enough for this number. Therefore a larger number of curves are needed, increasing the number it takes to complete. 
20150715, 22:55  #30 
Tribal Bullet
Oct 2004
3555_{10} Posts 
You don't have an hour to factor this yourself?

20150715, 23:46  #31 
"Frank <^>"
Dec 2004
CDP Janesville
84A_{16} Posts 

20150716, 10:04  #32 
Feb 2013
755_{8} Posts 
I notice the factorization of the remaining C103.
Thank you very much for doing that. Appreciated. 
20150717, 02:28  #33 
Dec 2012
117_{16} Posts 
Here is another interesting one. I have recently stumbled onto this C81 (link). This will be a difficult one to crack. In fact, it will likely take longer than the age of the universe to factor. I have already started trial factoring with my pocket calculator, and will let you all know of any results.

Thread Tools  
Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Can Pollard Rho cycles be used to find a factor?  wwf  Factoring  26  20130930 04:24 
PFGW can't find a small factor.  Arkadiusz  Software  7  20130218 12:43 
Chance to find an ndigit factor with ECM  RedGolpe  Factoring  4  20070323 15:24 
How much ECM does it take to find a given factor?  geoff  Factoring  5  20040929 20:14 
Where I find the best program to it factor keys? I use AMD.  chrow  Factoring  5  20040219 10:15 