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-   -   S/R Base 5 Primes reported in 2017+ (https://www.mersenneforum.org/showthread.php?t=23446)

 TheCount 2018-06-16 08:04

S/R Base 5 Primes reported in 2017+

Congratulations to Frank Schwegler for finding the 1st SR5 prime of 2017.
The prime 171362*5^2400996-1 found on 25 August 2017 eliminates k=171362 from the base 5 Riesel problem. The prime is 1,678,230 digits long and entered Chris Caldwell's “The Largest Known Primes Database” ([URL]http://primes.utm.edu/primes[/URL]) ranked 57th overall. 73 k's then remained in the Riesel Base 5 Problem.

Congratulations to Håkan Lind for finding the 2nd SR5 prime of 2017.
The prime 301562*5^2408646-1 found on 17 September 2017 eliminates k=301562 from the base 5 Riesel problem. The prime is 1,683,577 digits long and entered Chris Caldwell's “The Largest Known Primes Database” ([URL]http://primes.utm.edu/primes[/URL]) ranked 57th overall. 72 k's now remain in the Riesel Base 5 Problem. The base 5 Sierpinski problem has 33 k's remaining.

Primegrid is currently running a 5 day challenge on the Sierpinski / Riesel Base 5 (SR5) project, ends 19th June 2018 00:00 UTC.

 pepi37 2018-06-19 19:44

And new prime in this class is fall!

 pepi37 2018-06-22 13:03

And another one :)
After long time two primes in difference of few days.

 TheCount 2018-06-24 05:22

S/R Base 5 Primes reported in 2018

Congratulations to Selya Tsuji for finding the 1st SR5 prime of 2018.
The prime 327926*5^2542838-1 found on 19 June 2018 eliminates k=327926 from the base 5 Riesel problem. The prime is 1,777,374 digits long and entered Chris Caldwell's “The Largest Known Primes Database” ([URL]http://primes.utm.edu/primes[/URL]) ranked 60th overall. 71 k's now remain in the Riesel Base 5 Problem.

Congratulations to Jiří Bočan for finding the 2nd SR5 prime of 2018.
The prime 81556*5^2539960+1 found on 20 June 2018 eliminates k=81556 from the base 5 Sierpinski problem. The prime is 1,775,361 digits long and entered Chris Caldwell's “The Largest Known Primes Database” ([URL]http://primes.utm.edu/primes[/URL]) ranked 61st overall. 32 k's now remain in the Sierpinski Base 5 Problem.

Both of these primes were found just after the Primegrid SR5 challenge.

 DukeBG 2018-06-25 11:27

To be pedantic, both workunits were sent out [i]during[/i] the challenge :)

 TheCount 2018-08-05 01:18

S/R Base 5 Primes reported in 2018

Congratulations to Honza Cholt for finding the 3rd SR5 prime of 2018.
The prime 66916*5^2628609-1 found on 29 July 2018 eliminates k=66916 from the base 5 Riesel problem. The prime is 1,837,324 digits long and entered Chris Caldwell's “The Largest Known Primes Database” ([URL]http://primes.utm.edu/primes[/URL]) ranked 59th overall. 70 k's now remain in the Riesel Base 5 Problem.

 TheCount 2018-09-16 01:10

S/R Base 5 Prime reported in 2018

Congratulations again to Honza Cholt for finding the 4th SR5 prime of 2018.
The prime 194368*5^2638045-1 found on 15 August 2018 eliminates k=194368 from the base 5 Riesel problem. The prime is 1,843,920 digits long and entered Chris Caldwell's “The Largest Known Primes Database” ([URL]http://primes.utm.edu/primes[/URL]) ranked 60th overall. 69 k's now remain in the Riesel Base 5 Problem.

 pepi37 2019-04-27 07:33

And we have new SR5 prime!

[B][URL="http://primes.utm.edu/primes/page.php?id=126425"]138514*5^2771922+1[/URL][/B] found by Ken Ito on 26 April 2019

1937496 digits, position 63

 unconnected 2019-04-27 10:23

[QUOTE=pepi37;514878]And we have new SR5 prime!

[B][URL="http://primes.utm.edu/primes/page.php?id=126425"]138514*5^2771922+1[/URL][/B] found by Ken Ito on 26 April 2019

1937496 digits, position 63[/QUOTE]
Wow! I'm the doublechecker for this prime on Primegrid. :cool:

 pepi37 2019-04-27 18:04

[QUOTE=unconnected;514899]Wow! I'm the doublechecker for this prime on Primegrid. :cool:[/QUOTE]
Use -t option and be faster next time!

 pepi37 2019-06-21 18:12

And new one is arrived :)

[URL]https://primes.utm.edu/primes/page.php?id=126564[/URL]

88444 · 5^2799269 - 1

 rudy235 2019-06-21 23:15

[URL]https://primes.utm.edu/primes/page.php?id=126564[/URL]

88444 · 5[SUP]2799269[/SUP] - 1

1956611 digits Jun 2019

It is the largest SR5 prime and the third largest prime of 2019

it eliminates k=88444 from the base 5 Reisel Problem.

 pepi37 2019-06-25 08:07

And another hit :)

[url]https://primes.utm.edu/primes/page.php?id=126585[/url]

322498 · 52800819 - 1 is prime :)

 LaurV 2019-06-27 05:37

[QUOTE=pepi37;520028]
322498 · 52800819 (sic) - 1 is prime :)[/QUOTE]
That is divisible by 7 :razz:

 gd_barnes 2019-06-27 07:56

Pepi,

Please use the exponentiation symbol. Thanks.

 rudy235 2019-06-27 22:17

[QUOTE=gd_barnes;520164]Pepi,

Please use the exponentiation symbol. Thanks.[/QUOTE]

I never fail to do that,

 pepi37 2020-03-05 21:05

And new hit in SR5... prime will be verified soon :)

[url]https://primes.utm.edu/primes/page.php?id=130732[/url]

 axn 2020-03-10 09:50

Apparently there is another one?

[url]https://primes.utm.edu/primes/page.php?id=130751[/url]

146264*5^2953282-1

 JeppeSN 2020-03-14 10:25

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

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

/JeppeSN

 JeppeSN 2020-03-19 19:53

Fourth one, 207494*5^3017502 - 1.

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

/JeppeSN

 kar_bon 2020-05-04 21:45

Seems this was not reported here yet:

[url='https://primes.utm.edu/primes/page.php?id=130869']118568 * 5^3112069+1[/url] is prime, found on 2020-05-01

 rudy235 2022-02-18 22:12

[COLOR="Red"]Moderators: I am not too sure if this is the right (or best) thread to post this but please move it if required.[/COLOR]

A new Sierpinski/Riesel Base 5 has been found (verification pending)

#23 in the list currently 3622 · 5[SUP]7558139[/SUP] - 1
5282917 Digits L4965 (Ryan Propper) Feb 2022

This eliminates the smallest k in the list =3622 Riesel base 5

Congratulations to Ryan Propper.

 pinhodecarlos 2022-02-19 12:15

Congratulations Dr. Ryan.

 kar_bon 2022-06-16 13:02

One down for the Riesel-base 5 conjecture:

[url='https://primes.utm.edu/primes/page.php?id=134054']64598 * 5^3769854-1[/url] is prime, 2,635,020 digits, found on 2022-06-14 by PrimeGrid.

Curious: the 5 digits of the k-value appear also in the n-value.

Awaiting official announcement, still some tasks open for this k.

 rudy235 2022-06-17 03:40

[QUOTE=kar_bon;607981]One down for the Riesel-base 5 conjecture:

[url='https://primes.utm.edu/primes/page.php?id=134054']64598 * 5^3769854-1[/url] is prime, 2,635,020 digits, found on 2022-06-14 by PrimeGrid.

Curious: the 5 digits of the k-value appear also in the n-value.

Awaiting official announcement, still some tasks open for this k.[/QUOTE]

Congratulations!
This is the 97th prime with between 2 million and 3 million digits.

There are 10 primes in total (in that range) of the form k* 5^n +/- 1. (8 with -1 and 2 with +1)

 gd_barnes 2022-06-20 10:05

[QUOTE=kar_bon;607981]One down for the Riesel-base 5 conjecture:

[URL="https://primes.utm.edu/primes/page.php?id=134054"]64598 * 5^3769854-1[/URL] is prime, 2,635,020 digits, found on 2022-06-14 by PrimeGrid.

Curious: the 5 digits of the k-value appear also in the n-value.

Awaiting official announcement, still some tasks open for this k.[/QUOTE]
Even more curious: The digits 3 through 9 all occur 1 time in the n-value.

 pepi37 2022-06-20 21:59

And there is new one :)

[URL]https://primes.utm.edu/primes/page.php?id=134068[/URL]

63838 *5^3887851-1

2717497 digits, current 99 rank

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