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Forum: Conjectures 'R Us 2020-06-30, 23:12
Replies: 5
Views: 254
Posted By JeppeSN
Smile Not sure about the test limit. The BOINC server...

Not sure about the test limit. The BOINC server is at http://boincvm.proxyma.ru:30080/test4vm/server_status.php, the subproject has the name "LLR2 testing", but I do not think the search limit it...
Forum: Conjectures 'R Us 2020-06-30, 21:06
Replies: 5
Views: 254
Posted By JeppeSN
Red face PrimeGrid work on 90646*2^n + 1 and 101746*2^n + 1

In the context of the PrimeGrid forum, the idea to find additional primes in the series 45323*2^n + 1 and
50873*2^n + 1, along with others, came up. They both produce "trivial" primes for n=1.
...
Forum: Proth Prime Search 2020-06-20, 07:55
Replies: 5
Views: 337
Posted By JeppeSN
If you consider the numbers 2^(4k+2) + 1, there...

If you consider the numbers 2^(4k+2) + 1, there are two kinds of algebraic factorizations for them. One is because 4k+2 = 2(2k+1), so the exponent has an odd divisor, therefore:

2^(4k+2) + 1 =...
Forum: Proth Prime Search 2020-06-15, 17:42
Replies: 5
Views: 337
Posted By JeppeSN
Thumbs up That sounds correct. In fact it seems the...

That sounds correct. In fact it seems the Gaussian Mersenne norms includes a bit more candidates, namely 2^{2k+1} ± 2^{k+1} + 1 where the sign of the middle term is picked such that the candidate is...
Forum: Math 2020-06-15, 15:26
Replies: 15
Views: 832
Posted By JeppeSN
This may seem silly, but I ran a test with PFGW...

This may seem silly, but I ran a test with PFGW (slow, one CPU thread) on the remaining number. It took several weeks. Here is the result (PFGW does a 3-PRP test by default):


PFGW Version...
Forum: Math 2020-06-10, 13:38
Replies: 12
Views: 369
Posted By JeppeSN
Thumbs up According to...

According to https://mathshistory.st-andrews.ac.uk/HistTopics/Perfect_numbers/, Ismail ibn Ibrahim ibn Fallus (1194-1239) knew the first seven perfect numbers many years before Pietro Cataldi...
Forum: Math 2020-05-17, 21:07
Replies: 15
Views: 832
Posted By JeppeSN
Yes, I wonder if there is any explanation why the...

Yes, I wonder if there is any explanation why the four of them are prime squares. Apparently not. I did check that 2^74207283 - 7 is not a square, ha ha.

Edit: It has been proved...
Forum: Math 2020-05-17, 20:59
Replies: 15
Views: 832
Posted By JeppeSN
Updated with the latest factor from kruoli. ...

Updated with the latest factor from kruoli.

The only pending is 2^74207282 - 3. The same one that causes trouble with right perfect primes...
Forum: Math 2020-05-17, 18:02
Replies: 15
Views: 832
Posted By JeppeSN
Thumbs up Impressive. Can they be guaranteed to be minimal?...

Impressive. Can they be guaranteed to be minimal?

Only one composite without known factor, and one for which it is not known if it is prime or not. Updating:

p: factor of 2^{p+1} - 3...
Forum: Math 2020-05-17, 10:26
Replies: 15
Views: 832
Posted By JeppeSN
Found a factor of one of them: p: ...

Found a factor of one of them:

p: factor of 2^{p+1} - 3
----------------------------------
2: prime
3: prime
5: prime
7: 11
13: prime
...
Forum: Other Mathematical Topics 2020-05-17, 09:09
Replies: 2
Views: 3,673
Posted By JeppeSN
Arrow In most cases, just correct the wrong data, and...

In most cases, just correct the wrong data, and write in the Extensions section what you did. E.g. write "Wrong entries a(10)-a(20) corrected and additional entries added by" and your name will be...
Forum: Math 2020-05-17, 07:39
Replies: 15
Views: 832
Posted By JeppeSN
Cool Mersenne prime in a Cunningham chain

Often when a Mersenne prime M = 2^p - 1 is found, we check also the numbers M - 2 (twin), (M + 2)/3 (Wagstaff) and M*(M + 1)/2 + 1 (right perfect) to make sure M does not have a "companion" prime.
...
Forum: Software 2020-04-18, 12:20
Replies: 407
Views: 24,988
Posted By JeppeSN
Question Silly question: Which is the preferred place to...

Silly question: Which is the preferred place to download from if I only care about the Windows (x64) binaries, not the source?

On https://www.mersenneforum.org/rogue/mtsieve.html there is a file...
Forum: Riesel Prime Search 2020-04-01, 08:53
Replies: 206
Views: 22,700
Posted By JeppeSN
Arrow There is already a newer and bigger one,...

There is already a newer and bigger one, 9*2^13334487 + 1 (https://primes.utm.edu/primes/page.php?id=130806). He has found 9 huge Proth primes with k in { 9, 11, 13 } in the month of March.

Ryan...
Forum: Sierpinski/Riesel Base 5 2020-03-19, 19:53
Replies: 20
Views: 14,752
Posted By JeppeSN
Fourth one, 207494*5^3017502 - 1. ...

Fourth one, 207494*5^3017502 - 1.

https://primes.utm.edu/primes/page.php?id=130783

/JeppeSN
Forum: Riesel Prime Search 2020-03-16, 17:13
Replies: 206
Views: 22,700
Posted By JeppeSN
Question What ranges was Propper searching, and did he...

What ranges was Propper searching, and did he keep the residues of all the composite candidates he must have covered? This information could be useful to PrimeGrid which is planning to search and...
Forum: Sierpinski/Riesel Base 5 2020-03-14, 10:25
Replies: 20
Views: 14,752
Posted By JeppeSN
Thumbs up And the third one of this month: 238694*5^2979422...

And the third one of this month: 238694*5^2979422 - 1

https://primes.utm.edu/primes/page.php?id=130771

/JeppeSN
Forum: Math 2020-02-07, 16:26
Replies: 36
Views: 4,695
Posted By JeppeSN
forprime(p=2,2^(67/2),(2^67-1)%p==0&&return(p)) ...

forprime(p=2,2^(67/2),(2^67-1)%p==0&&return(p))

(PARI/GP) That is the worst method I can imagine. It tries every prime (ignoring the fact that Mersenne divisors have a special form), it even...
Forum: Computer Science & Computational Number Theory 2020-01-25, 19:01
Replies: 79
Views: 10,498
Posted By JeppeSN
Does this simply say that F30 is composite, or...

Does this simply say that F30 is composite, or does it help to determine whether the cofactor F30 / ((149041*2^32 + 1)*(127589*2^33 + 1)) is composite (Suyama...
Forum: FermatSearch 2020-01-25, 18:03
Replies: 302
Views: 36,460
Posted By JeppeSN
Lightbulb Yes, your number 3*2^5523861 + 1 is composite,...

Yes, your number 3*2^5523861 + 1 is composite, because PrimeGrid has established the primality status of all numbers 3*2^n ± 1 for n up to over 15.5 million, see their page stats_321_llr...
Forum: FermatSearch 2020-01-25, 17:04
Replies: 302
Views: 36,460
Posted By JeppeSN
PrimeGrid's official announcement is here and can...

PrimeGrid's official announcement is here and can be found in this thread of theirs (https://www.primegrid.com/forum_thread.php?id=8997). /JeppeSN
Forum: FermatSearch 2020-01-24, 23:41
Replies: 302
Views: 36,460
Posted By JeppeSN
Post It is the same Scott Brown who found another...

It is the same Scott Brown who found another Fermat factor, 9*2^2543551+1, back in 2011, in a similar way.

In PrimeGrid, the participants detect the primality (two persons do it concurrently, the...
Forum: FermatSearch 2020-01-24, 13:52
Replies: 302
Views: 36,460
Posted By JeppeSN
Wink Good old F(5523858): I always thought it would be...

Good old F(5523858): I always thought it would be composite, but I did not expect such a tiny prime divisor! /JeppeSN
Forum: Math 2019-05-10, 05:09
Replies: 23
Views: 2,004
Posted By JeppeSN
Smile If you let n run through all odd composite 3-PRP,...

If you let n run through all odd composite 3-PRP, and test if znoroder(Mod(2, n)) is a prime, you get the counterexamples in a sorted way. The sequence goes:

10974881, 193949641, 717653129,...
Forum: Math 2019-05-10, 00:19
Replies: 23
Views: 2,004
Posted By JeppeSN
Cool 239 is a prime. The Mersenne number 2^239-1 has...

239 is a prime. The Mersenne number 2^239-1 has as a factor the number 10974881. That number, 10974881, is really a 3-PRP. So by your belief, 10974881 should be a prime.

But as you may have...
Showing results 1 to 25 of 115

 
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