20140714, 04:56  #1 
"Gary"
May 2007
Overland Park, KS
12,547 Posts 
Doublecheck efforts; S66/S79 to start with
We are starting this thread for all doublecheck efforts. To begin with, as stated in the news thread, S66 and S79 have problems and will need some k's retested. Later on, we will add other bases when potential problems are identified or just to simply confirm past work done.
Attached here are two files that each contain several thousand k's. The S66 k's need to be tested for n=1000 to n=25K and the S79 k's need to be tested for n=1000 to n=50K in order to catch them up with all other k's search depth on the conjectures. Note that these k's have not been searched for n>1K so this is not a true doublecheck effort. They were newly identified as k's that were erroneously removed as a result of incorrect small composite "primes" that were found by a bad version of PFGW. Initially I was going to start these myself but won't be able to get to them for 23 weeks so I'm opening them up to anyone who has a few spare cores available. Any help would be greatly appreciated to get these largeconjectured bases corrected. S66 Code:
krange nrange reservation last status 1700K 1K25K firejuggler (complete) 700K21M 1K25K Lennart (complete) 21Mend 1K25K Mathew (complete) Code:
krange nrange reservation last status 12.2M 1K50K Lennart (complete) 2.2Mend 1K50K Mathew (complete) Last fiddled with by gd_barnes on 20140803 at 08:53 Reason: update status 
20140714, 06:35  #2 
"Gary"
May 2007
Overland Park, KS
12,547 Posts 
Mathew,
I added nrange to the reservation list in case people want to take a wider range of k to a smaller search depth. I'm assuming that you're searching to the max search depth of the conjectures. Gary 
20140714, 09:45  #3 
"Lennart"
Jun 2007
460_{16} Posts 
I am taking s66
121M 1K25K Lennart s79 12.2M 1k50k Lennart 
20140714, 11:58  #4 
"Vincent"
Apr 2010
Over the rainbow
37×79 Posts 
Arg! Oh well, since Lennart take everything left, I guess i'll stop what I was testing.
I took all k upto 700 000 from N=1k to N=2k: 126 primes found , 90 different sequences. PFGW Version 3.7.7.64BIT.20130722.Win_Dev [GWNUM 27.11] Last fiddled with by firejuggler on 20140714 at 11:59 
20140714, 12:46  #5  
"Lennart"
Jun 2007
1120_{10} Posts 
Quote:
Sorry... I have not started any tests I am only sieving at this point. I sieve all reserved range on s66 1k25k in one file. If you like to continue the search up tp k = 700k I can cut that out to you. Just one question . Are you going to do them to 25K ? Lennart Last fiddled with by Lennart on 20140714 at 12:49 

20140714, 12:59  #6 
"Vincent"
Apr 2010
Over the rainbow
37×79 Posts 
yup, i'll do them up to n=25k.
there was 224 sequence between 470 and 686081 (last k before 700 000). Continuing with the 134 sequences left. 
20140714, 13:30  #7 
"Lennart"
Jun 2007
2140_{8} Posts 
Changing this
Releasing 121M 1K25K Lennart and taking s66 700k21M 1K25K Lennart Last fiddled with by Lennart on 20140714 at 13:30 
20140714, 18:10  #8  
"Gary"
May 2007
Overland Park, KS
30403_{8} Posts 
Quote:
Please reserve a range before working on it. It creates extra work for other searchers and possibly for yourself. Second, I appreciate that you removed the higher primes for k's with multiple primes. It saves me admin time. But I would strongly suggest simply stopping the search of a k with a prime to save you CPU time and the task of creating and sending an extra file to me. Here is how to do it: Replace the header in your sieve file with this: ABC $a*66^$b+1 // {number_primes,$a,1} With this header, the program will stop searching a k when a prime is found for it. This info. can be found in the file "abcfileformats.txt" in the PFGW download directory. Note that the more recent versions of PFGW can be stopped and restarted and it will still "know" which k's have primes. (It reads the pfgw.log and/or pfgwprime.log files so those will need to be left there if the program is stopped.) Earlier versions would "forget" which k's had primes if stopped. Gary Last fiddled with by gd_barnes on 20140714 at 18:47 

20140714, 18:37  #9 
"Gary"
May 2007
Overland Park, KS
12,547 Posts 
Thank you everone for stepping in to get these bases corrected quickly.

20140714, 21:09  #10 
Just call me Henry
"David"
Sep 2007
Liverpool (GMT/BST)
6,217 Posts 
I suspect a reasonable way to detect whether a base has had a faulty version used on it would be to doublecheck the small ns for the current remaining ks. If any primes are found then that base/range needs redoing.

20140714, 23:14  #11 
"Gary"
May 2007
Overland Park, KS
12,547 Posts 
That's how Phillip found the issue with S66/S79. For the most part, when the issue appears, that would work because the problem is prevalent enough. But if it is a sparse problem on some bases, I would still like to know if there are any differences, even if erroneously removed k's eventually had a larger prime causing there to be no issues found when doing your suggested method. On large conjectured bases, what I'm doing is just testing k<100K to n=100 and doing the compare. That is sufficient enough for my comfort level and it doesn't take too long.
Last fiddled with by gd_barnes on 20140714 at 23:21 
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