mersenneforum.org  

Go Back   mersenneforum.org > Search Forums

Showing results 1 to 25 of 109
Search took 0.03 seconds.
Search: Posts Made By: JeppeSN
Forum: Math 2020-05-17, 21:07
Replies: 13
Views: 641
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: 13
Views: 641
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: 13
Views: 641
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: 13
Views: 641
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: 3,288
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: 13
Views: 641
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: 353
Views: 22,738
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: 204
Views: 21,978
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: 13,544
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: 204
Views: 21,978
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: 13,544
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: 4,102
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: 10,239
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: 301
Views: 35,871
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: 301
Views: 35,871
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: 301
Views: 35,871
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: 301
Views: 35,871
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: 1,939
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: 1,939
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...
Forum: Puzzles 2019-03-30, 06:24
Replies: 6
Views: 673
Posted By JeppeSN
Thumbs up In the Julian calendar, the leap year pattern...

In the Julian calendar, the leap year pattern repeats after 4 years which is 1,461 days. Now, when you consider weekdays, with 7 days in each week, you have to consider whether or not 7 divides...
Forum: News 2019-01-12, 17:43
Replies: 270
Sticky: Lucky 13
Views: 25,675
Posted By JeppeSN
Cool Not sure I know what you mean. With k=1 you are...

Not sure I know what you mean. With k=1 you are describing the smaller example. It gives [$]2^k+k = 3[/$] and [$]2^k=2[/$] and the prime (seven) is [$$]M(3)=2^3-1=2\cdot 2^2 - 1=W(2)[/$$]
The other...
Forum: News 2019-01-11, 22:19
Replies: 270
Sticky: Lucky 13
Views: 25,675
Posted By JeppeSN
philmoore is right the Manchester Mark 1...

philmoore is right the Manchester Mark 1 (https://en.wikipedia.org/wiki/Manchester_Mark_1) was used to search for Mersenne primes (however did not find any new ones) before the SWAC...
Forum: News 2019-01-06, 17:45
Replies: 270
Sticky: Lucky 13
Views: 25,675
Posted By JeppeSN
However, Robinson...

However, Robinson (https://en.wikipedia.org/wiki/Raphael_M._Robinson) (the first person to use a computer for the Mersenne search) extended the number of known Mersenne primes from 12 to 17 in just...
Forum: News 2018-12-30, 15:16
Replies: 96
Views: 3,791
Posted By JeppeSN
I am not sure I understand. What are [$]x[/$],...

I am not sure I understand. What are [$]x[/$], [$]y[/$] and [$]z[/$] here? If one of [$]y[/$] and [$]z[/$] is odd and the other one even, the first one is false. And the second one is false if I pick...
Forum: News 2018-12-29, 18:39
Replies: 96
Views: 3,791
Posted By JeppeSN
Thumbs up I do not know what "empirically" means in the...

I do not know what "empirically" means in the preceding posts, but for any odd [$]p[/$] we have [$$]2^p\equiv(-1)^p = -1 \pmod 3[/$$] and also for any [$]p\ge 3[/$] we have [$$]2^p=2^3\cdot...
Showing results 1 to 25 of 109

 
All times are UTC. The time now is 06:33.

Sun Jun 7 06:33:00 UTC 2020 up 74 days, 4:06, 0 users, load averages: 1.29, 1.71, 1.71

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.