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 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 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 ...
 2020-05-17, 09:09 Replies: 2 Views: 3,288 Posted By JeppeSN 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 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 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 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 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 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...
 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 Sticky: New Fermat factors Views: 35,871 Posted By JeppeSN 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 Sticky: New Fermat factors 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 Sticky: New Fermat factors Views: 35,871 Posted By JeppeSN 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 Sticky: New Fermat factors Views: 35,871 Posted By JeppeSN 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 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 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 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 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 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...
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