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.
For details, please read the post in the PrimeGrid forum:
[URL]http://www.primegrid.com/forum_thread.php?id=8027[/URL]

And new prime in this class is fall!

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

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.

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

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.

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.

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=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:

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

And new one is arrived :)


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


88444 · 5^2799269 - 1

[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.

And another hit :)


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


322498 · 52800819 - 1 is prime :)

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

Pepi,


Please use the exponentiation symbol. Thanks.

[QUOTE=gd_barnes;520164]Pepi,


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

I never fail to do that,

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


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

Apparently there is another one?

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

146264*5^2953282-1

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

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

/JeppeSN

Fourth one, 207494*5^3017502 - 1.

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

/JeppeSN

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

[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.

Congratulations Dr. Ryan.

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=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)

[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.

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