Added [URL="https://primes.utm.edu/primes/page.php?id=134739"]134739[/URL] : 471*2^2220478-1 (668434 digits)

Max found:
877*2^1927713-1 is prime

Max found:
771*2^1933543-1 is prime
859*2^1935299-1 is prime

Max found:
765*2^1937364-1 is prime
743*2^1938344-1 is prime

Max found:
607*2^1942565-1 is prime
603*2^1944086-1 is prime

Max found:
949*2^1944741-1 is prime

Max found:
675*2^1949015-1 is prime
829*2^1953661-1 is prime

Max found:
801*2^1956058-1 is prime

Max found:
727*2^1958505-1 is prime
915*2^1958653-1 is prime
609*2^1961889-1 is prime

Added [URL="https://primes.utm.edu/primes/page.php?id=134785"]134785[/URL] : 493*2^2238775-1 (673942 digits)

Max found:
657*2^1964578-1 is prime
921*2^1966634-1 is prime
611*2^1966866-1 is prime

Max found:
651*2^1974918-1 is prime

Added [URL="https://primes.utm.edu/primes/page.php?id=134794"]134794[/URL] : 507*2^2244237-1 (675586 digits)

Max found:
675*2^1982779-1 is prime

Added [URL="https://primes.utm.edu/primes/page.php?id=134805"]134805[/URL] : 571*2^2248701-1 (676930 digits)

Max found:
781*2^1993173-1 is prime

Added [URL="https://primes.utm.edu/primes/page.php?id=134812"]134812[/URL]: 655 *2^1993685-1 (600612 digits)

Max at the last minute on drive 14 finds:
841*2^1999951-1 is prime

Max found:
377*2^2262094-1 is prime

Added [URL="https://primes.utm.edu/primes/page.php?id=134823"]134823[/URL] : 489*2^2255331-1 (678925 digits)

Added [URL="https://primes.utm.edu/primes/page.php?id=134824"]134824[/URL] : 403*2^2254355-1 (678632 digits)

Max found:
351*2^2331311-1 is prime

Max found:
369*2^2436949-1 is prime

Max found:
373*2^2457859-1 is prime

Added [URL="https://primes.utm.edu/primes/page.php?id=134954"]134954[/URL] : 493*2^2269427-1 (683169 digits)

Max found:
369*2^2551955-1 is prime

Max found:
357*2^2568110-1 is prime

Max found:
915*2^2009048-1 is prime

377*2^2607856-1 is prime

Max found:
381*2^2801281-1 is prime

Max found:
381*2^2820157-1 is prime

Max found:
393*2^2828738-1 is prime

Max found:
353*2^2888332-1 is prime

Added 135677 : 467*2^2304298-1 (693666 digits)

Max found:
379*2^2911423-1 is prime

Added 135692 : 553*2^2306343-1 (694282 digits)

Max found:
391*2^2925759-1 is prime

Added [URL="https://primes.utm.edu/primes/page.php?id=135720"]135720[/URL] : 447*2^2308104-1 (694812 digits)

Max found:
395*2^2961370-1 is prime

Max found:
369*2^2968175-1 is prime

Max found:
367*2^2979033-1 is prime
357*2^2980540-1 is prime

Max found:
811*2^2023885-1 is prime

Added [URL="http://primes.utm.edu/primes/page.php?id=135743"]135743[/URL] : 495*2^2313462-1 (696425 digits)

Max found:
615*2^2028140-1 is prime

Max found:
921*2^2030231-1 is prime
767*2^2030354-1 is prime

The Riesel prime tables posted by Cybertronic were moved to a new thread here:
[url]https://mersenneforum.org/showthread.php?t=28526[/url]

Max found:
777*2^2041710-1 is prime

Added [URL="https://t5k.org/primes/page.php?id=135795"]135795[/URL] : 421*2^2324375-1 (699710 digits)

Max found:
909*2^2056937-1 is prime

[url='https://t5k.org/primes/page.php?id=135805']909*2^2056937-1[/url] seems composite but verification status is PRP.

[QUOTE=kar_bon;626979][url='https://t5k.org/primes/page.php?id=135805']909*2^2056937-1[/url] seems composite but verification status is PRP.[/QUOTE]

I just now double-checked it. LLR version 3.8.23 says otherwise:

909*2^2056937-1 is prime! (619203 decimal digits) Time : 1299.213 sec.

Max's machines have been quite stable. He just now found another prime and I also verified that it is prime. I'll report it in the next post.

The new top-5000 site appears to be wrong! They need to work on their verification process. It takes many hours for the tests to start, it takes too long to run the test (over an hour for this one), and now it outputs the wrong result.

Anyone else care to test this?

Edit: I just now used their "let us know if anything isn't working" process to Email them about the problem.

Max found:
813*2^2060392-1 is prime

Double-checked by LLR 3.8.23.

[QUOTE=gd_barnes;626984]I just now double-checked it. LLR version 3.8.23 says otherwise:

909*2^2056937-1 is prime! (619203 decimal digits) Time : 1299.213 sec.

Max's machines have been quite stable. He just now found another prime and I also verified that it is prime. I'll report it in the next post.

The new top-5000 site appears to be wrong! They need to work on their verification process. It takes many hours for the tests to start, it takes too long to run the test (over an hour for this one), and now it outputs the wrong result.

Anyone else care to test this?

Edit: I just now used their "let us know if anything isn't working" process to Email them about the problem.[/QUOTE]

Could be a hardware glitch on the Digital Ocean cloud ressource used by the new t5k.org. The prime is most likely good. Administrators of t5k.org are aware and have up to now prevented the deletion of the entry.

Note that a proof of such c=-1 candidate with Lucas-Lehmer-Riesel does not allow Gerbicz checks to catch hardware glitches. So the best way to prove primality seems to be to repeat the run on several different [I]reliable[/I] machines.

/JeppeSN

[QUOTE=JeppeSN;626986]Could be a hardware glitch on the Digital Ocean cloud ressource used by the new t5k.org. The prime is most likely good. Administrators of t5k.org are aware and have up to now prevented the deletion of the entry.

Note that a proof of such c=-1 candidate with Lucas-Lehmer-Riesel does not allow Gerbicz checks to catch hardware glitches. So the best way to prove primality seems to be to repeat the run on several different [I]reliable[/I] machines.

/JeppeSN[/QUOTE]

Thanks for the update and info!

[QUOTE=gd_barnes;626984]I just now double-checked it. LLR version 3.8.23 says otherwise:

909*2^2056937-1 is prime! (619203 decimal digits) Time : 1299.213 sec.

Anyone else care to test this?[/QUOTE]

I also verified it.

C:\prpnet\prpclient-4>cllr64.exe -v
LLR Program - Version 3.8.23, using Gwnum Library Version 29.8

C:\prpnet\prpclient-4>cllr64.exe -t4 -d -q"909*2^2056937-1"
Starting Lucas Lehmer Riesel prime test of 909*2^2056937-1
Using AVX FFT length 140K, Pass1=448, Pass2=320, clm=1, 4 threads
V1 = 3 ; Computing U0...done.
909*2^2056937-1 is prime! (619203 decimal digits) Time : 1001.568 sec.

Regards Odi

I ran it using my copy of PFGW (which appears to be the same version as T5K), and I got a bunch of round-off errors:

[code]$ ./pfgw -tp -q"909*2^2056937-1"
PFGW Version 4.0.1.64BIT.20191203.x86_Dev [GWNUM 29.8]

Primality testing 909*2^2056937-1 [N+1, Brillhart-Lehmer-Selfridge]
Running N+1 test using discriminant 5, base 1+sqrt(5)
Detected in MAXERR>0.45 (round off check) in Exponentiator::Iterate
Iteration: 18/2056948 ERROR: ROUND OFF 0.5>0.45
(Test aborted, try again using the -a1 switch)
Running N+1 test using discriminant 5, base 1+sqrt(5)
Detected in MAXERR>0.45 (round off check) in Exponentiator::Iterate
Iteration: 19/2056948 ERROR: ROUND OFF 0.5>0.45
(Test aborted, try again using the -a2 (or possibly -a0) switch)
Running N+1 test using discriminant 5, base 1+sqrt(5)
^C1: 909*2^2056937-1 5000/2056948 mro=0.5
Ctrl-C detected, shutting down the program.
[/code]

I re-ran with [c]-a2[/c]:

[code]$ ./pfgw -tp -q"909*2^2056937-1" -a2
PFGW Version 4.0.1.64BIT.20191203.x86_Dev [GWNUM 29.8]

Primality testing 909*2^2056937-1 [N+1, Brillhart-Lehmer-Selfridge]
Running N+1 test using discriminant 5, base 1+sqrt(5)
909*2^2056937-1 is prime! (3940.2488s+0.0006s)
[/code]

The bad result on t5k.org is reproducible, so not a random hardware glitch.

Thought to be related to the version of GWNUM used, on hardware where the AVX-512 instructions [I]are[/I] available.

If someone with some version of PFGW can test on AVX-512-capable hardware, with [C]-tp -q"909*2^2056937-1" -V[/C] where the -V seems to give info about choices made by GWNUM.

/JeppeSN

[CODE]$ ./pfgw64 -tp -q"909*2^2056937-1" -V
PFGW Version 4.0.4.64BIT.20221214.x86_Dev [GWNUM 30.11]

Primality testing 909*2^2056937-1 [N+1, Brillhart-Lehmer-Selfridge]
Running N+1 test using discriminant 5, base 1+sqrt(5)
Special modular reduction using AVX-512 FFT length 144K, Pass1=192, Pass2=768, clm=1 on 909*2^2056937-1
909*2^2056937-1 is prime! (1746.6204s+0.0004s)[/CODE]

I just got an Email from Reginald, the new top-5000 server admin, that the problem has been fixed.

The problem was related to having an older version of PFGW combined with AVX-512 hardware. They re-built PFGW from the latest source, installed it on the server, and confirmed the prime.

Thank you to the new top-5000 admins for taking care of this and to everyone else for verifying the prime! :smile:

[QUOTE=gd_barnes;626984]I just now double-checked it. LLR version 3.8.23 says otherwise:

909*2^2056937-1 is prime! (619203 decimal digits) Time : 1299.213 sec.

Max's machines have been quite stable. He just now found another prime and I also verified that it is prime. I'll report it in the next post.

The new top-5000 site appears to be wrong! They need to work on their verification process. It takes many hours for the tests to start, it takes too long to run the test (over an hour for this one), and now it outputs the wrong result.

Anyone else care to test this?

Edit: I just now used their "let us know if anything isn't working" process to Email them about the problem.[/QUOTE]
Ah, yes - I noticed the same issue last night. The top-5000 site sent me an automatic email informing me of the verification failure. I re-tested the candidate myself last night twice using different programs, the first time with the very latest LLR2 v1.3.3 (gwnum 30.11), and the second as an N+1 test with an older PFGW 3.7.10 (gwnum 28.7), similar to what the top-5000 site tried to run. Both confirmed primality without issue - although like others here, I did get several round-off errors during the PFGW test (which PFGW was able to detect and self-heal by going to a more cautious FFT).

I wouldn't be surprised if the reason the problem only showed up just now on this candidate is because it's most sensitive near an FFT boundary (where self-correcting roundoff errors like this are common - but might not be self-correcting if there's an underlying hardware/software issue).

I was going to email them myself about it today, but was busy for much of the day and by the time I checked in the evening, saw that the top-5000 site was already actively retrying it. (The first re-try failed again, but I saw another one was in progress, which ultimately turned out prime.) Now I see that's because Gary emailed them - thanks! :smile:

Glad to see the root cause was found and resolved (per Gary's note just above) - and that everyone here is so on top of this! I was wondering if it was something like an AVX-512 issue, as that's the only sort of issue I could imagine manifesting like this in a cloud-computing environment (where the hardware is invariably server-grade with ECC RAM, which prevents most "random" bit-flip errors).

Max found:
983*2^2064020-1 is prime

Added [URL="https://t5k.org/primes/page.php?id=135816"]135816[/URL] : 413*2^2327048-1 (700514 digits)

Added [URL="http://t5k.org/primes/page.php?id=135824"]135824[/URL] : 831*2^2070622-1 (623323 digits)

Max found:
867*2^2072142-1 is prime

Max found:
825*2^2075800-1 is prime

Max found:
777*2^2076841-1 is prime

Max found:
615*2^2089329-1 is prime

Added [URL="https://t5k.org/primes/page.php?id=135860"]135860[/URL] : 535*2^2338971-1 (704104 digits)

919*2^2097543-1 is prime

729*2^2097449-1 is prime

327*2^3006540-1 is prime (port 1468/drive #19)
633*2^2100738-1 is prime (port 2000/drive #18)
1001*2^2101062-1 confirmed prime (port 2000/drive #18, already-known prime from earlier efforts)

Luminescence has 2 primes to report. :-)

Added 135909 : 513*2^2348508-1 (706975 digits)
Added 135910 : 495*2^2343641-1 (705509 digits)

Uhhh, a bit late. Oops :blush:

Added 135934 : 423*2^2353447-1 (708461 digits)

Added 135935 : 523*2^2356047-1 (709244 digits)

Added 135952 : 561*2^2359543-1 (710296 digits)
Added 135953 : 465*2^2360088-1 (710460 digits)

From port 2000 (drive #18):
Added [url=https://t5k.org/primes/page.php?id=135961]135961[/url] : 981*2^2104657-1 (633568 digits)

Added 135988 : 475*2^2369411-1 (713267 digits)

Added 136020 : 423*2^2382134-1 (717097 digits)

Added 136047 : 427*2^2391685-1 (719972 digits)
Added 136048 : 453*2^2395836-1 (721222 digits)

Added 136058 : 419*2^2401672-1 (722978 digits)
Added 136059 : 511*2^2401795-1 (723016 digits)

Added 136103 : 539*2^2421556-1 (728964 digits)

Added 136106 : 433*2^2423839-1 (729651 digits)

Added 136115 : 527*2^2424868-1 (729961 digits)
Added 136116 : 539*2^2425704-1 (730213 digits)

Added 136120 : 541*2^2427667-1 (730804 digits)

753*2^2112554-1 is prime

Do you also test +1 for a twin-chance ?

[QUOTE=Cybertronic;631748]Do you also test +1 for a twin-chance ?[/QUOTE]

No we do not. Feel free to test any of them that you want to for a twin.

Added 136157 : 489*2^2442281-1 (735203 digits)

Added 136170 : 441*2^2449825-1 (737474 digits)

Added 136180 : 411*2^2457241-1 (739706 digits)
Added 136181 : 545*2^2457692-1 (739842 digits)

[QUOTE=gd_barnes;631737]753*2^2112554-1 is prime[/QUOTE]

All base 2 Riesel. This has the appearance of something which could be done with [I]PFGW[/I]. :cool:

Added 136197 : 465*2^2467625-1 (742832 digits)
Added 136198 : 561*2^2469713-1 (743461 digits)

Added 136226 : 429*2^2478139-1 (745997 digits)
Added 136227 : 483*2^2478266-1 (746036 digits)

Added 136229 : 527*2^2482876-1 (747423 digits)

Added 136247 : 413*2^2486596-1 (748543 digits)
Added 136248 : 483*2^2488154-1 (749012 digits)

Added 136260 : 531*2^2495930-1 (751353 digits)
Added 136261 : 477*2^2496685-1 (751580 digits)