20200704, 20:09  #771  
Just call me Henry
"David"
Sep 2007
Cambridge (GMT/BST)
5719_{10} Posts 
Quote:


20200705, 02:13  #772 
Jun 2012
Boulder, CO
181 Posts 
In case anyone is interested, here's the full msieve log for 732541^471.

20200802, 20:05  #773 
Apr 2006
2^{2}·23 Posts 
The new list of roadblock composites is here
http://www.lirmm.fr/~ochem/opn/mwrb2100.txt and the old one is here http://www.lirmm.fr/~ochem/opn/old_mwrb2100.txt Most of the changes are due to the recent factorizations of sigma(3^660) and sigma(732541^46). Notably, the weight of sigma(6115909044841454629^16) drops from 79580833 to 67959517 and the weight of sigma(127^192) drops from 29196565 to 14190689. 
20200803, 16:05  #774 
Just call me Henry
"David"
Sep 2007
Cambridge (GMT/BST)
7×19×43 Posts 
Are the files available that contain all the factors used in the proof?
How do you check that all the composites hit have been trial factored to at least the assumed level given that pfn doesn't output a file containing the composites hit(I suppose you could extract them from the log)? Does it even matter if there are unfound small factors in nonroadblock composites apart from them causing gcd errors? 
20200809, 21:03  #775  
Apr 2006
2^{2}·23 Posts 
My policy is to increase the lower bound by a factor 10^100 when the run takes less than one week.
A couple of years ago, it took 3 weeks to prove 10^2100. The goal of the run of july 2020 was to get the timing (it took 12 days) and to update the list of roadblocks. Some composites would have been needed in order to circumvent sigma(3^660) or sigma(732541^46) but are not needed elsewhere. They are not needed anymore and do not appear in the updated mwrb2100.txt Since the program was not aiming at a new lower bound, it was run with trial factoring up to 300 only, in order to catch the tiny factors that may cause the abundancy to exceed 2 (a higher trial limit or some ECM would slow things down). This produces a load of uninteresting factors. Trial factoring up to 10^10 is indeed required for roadblock composites. This is checked a posteriori. The list of useful factors has been updated: http://www.lirmm.fr/~ochem/opn/checkfacts.txt.gz Quote:
Most probably, the cofactor will be composite. In this case, a given factor \(P\) with \(d\) digits counts for \(d\) digits if \(P\) is in the unfactored part and counts for \(2d\) digits if \(P\) is in the factored part, because we can usually assume that \(P^2 \) divides the OPN. So finding \(P\) contributes only \(d\) digits to the 2100 digits, in only one or few branches of the proof tree. The composites worth considering are in mwrb2100.txt and t2100.txt 

20200810, 17:55  #776 
Dec 2017
3D_{16} Posts 
All of the remaining entries in the MWRB file have SNFS difficulty above 210.
That is about the upper limit of my resources and NFSNET has reserved the next one, so this is a good point to stop working on this file. 
Thread Tools  
Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Passive Pascal  Xyzzy  GPU Computing  1  20170517 20:22 
Tesla P100 — 5.4 DP TeraFLOPS — Pascal  Mark Rose  GPU Computing  52  20160702 12:11 
Nvidia Pascal, a third of DP  firejuggler  GPU Computing  12  20160223 06:55 
Calculating perfect numbers in Pascal  Elhueno  Homework Help  5  20080612 16:37 
Factorization attempt to a c163  a new Odd Perfect Number roadblock  jchein1  Factoring  30  20050530 14:43 