2*3^1010743-1 (482248 digits)

k=2 and k=4 @ base=3 tested continouously till n=990k (currently closing a gap till n=1M)

Wow, nice find Cruelty. Do you have a list of primes of this form?
-Curtis

[QUOTE=VBCurtis;270596]Wow, nice find Cruelty. Do you have a list of primes of this form?
-Curtis[/QUOTE]

Look [URL="http://oeis.org/A003307"]here[/URL] and [URL="http://oeis.org/A005540"]here[/URL] :smile:

Congrats to 12121 on a large k=121 prime found jointly with PrimeGrid:

121*2^4553899-1 (1370863 digits)

On 28 Feb 2012, 15:51:22, PrimeGrid’s 27121 Prime Search, through PRPNet and in collaboration with the 12121 Search (k=27 sister project), has found the mega prime: [B][URL="http://primes.utm.edu/primes/page.php?id=105209"]27*2^3855094-1[/URL][/B]
The prime is 1,160,501 digits long and enters Chris Caldwell's [B][URL="http://primes.utm.edu/primes"]The Largest Known Primes Database[/URL][/B] ranked 34th overall. This is PrimeGrid's 23rd mega prime.
The discovery was made by [B]Pietari Snow[/B] of Finland. More details and official announcement to come.



On 28 Feb 2012, PrimeGrid’s Primorial Prime Search, through PRPNet, has found a world record primorial prime: [B][URL="http://primes.utm.edu/primes/page.php?id=105273"]1098133#-1[/URL][/B]
The prime is 476,311 digits long and enters Chris Caldwell's [B][URL="http://primes.utm.edu/primes"]The Largest Known Primes Database[/URL][/B] ranked 1st for Primorial primes and 253rd overall.
The discovery was made by [B]James P. Burt[/B] of the Cayman Islands. More details and official announcement to come.
Congratulations Beyond!!!

Primorials
 

Yes, indeed, special congrats to Beyond for the new Primorial record! I think it takes time to test these numbers, and there are not so many of them. For almost 10 years, 2001-2010 not a single primorial prime was found!

[url]http://primes.utm.edu/top20/page.php?id=5[/url]

12 of top-20 primorials were found by Dubner, including two found in 1984, more than 27 years ago!

Congrats to Curtis on a nice Sophie-Germain pair, currently ranked 15th.

133603707*2^100013-1
133603707*2^100014-1

[QUOTE=Kosmaj;299772]Congrats to Curtis on a nice Sophie-Germain pair, currently ranked 15th.

133603707*2^100013-1
133603707*2^100014-1[/QUOTE]

Thanks! I tested one sieve (n=85001) to k=1G, and then sieved a new file from k=1 to k=2G; I found this pair after less than 5% of the file was tested. Slow going, since I'm using an Atom netbook for the newpgen work!
-Curtis

World Record GFN Prime Found...Twice!
 

[quote]Just prior to the start of the Alan Turing Year Challenge challenge, not one, but two GFN mega primes were found! When all is finalized, these will be the 11th and 12th largest primes found to date and will be the two largest primes found by PrimeGrid. These are each incredible finds!

Internal verification of these primes is ongoing, and for primes of this size will take a few days. Stay tuned for the official announcement.

There's still more than half of the challenge to go...Let's see if we can make it three (or more)! :)
[/quote]

[url]http://www.primegrid.com/forum_thread.php?id=4426[/url]

On 8 Aug 2012, 8:58:58 UTC, PrimeGrid’s Generalized Fermat Prime Search found the [B]largest known Generalized Fermat[/B] mega prime:
[B][URL="http://primes.utm.edu/primes/page.php?id=108818"]475856^524288+1[/URL][/B]

The prime is 2,976,633 digits long and enters Chris Caldwell's [B][URL="http://primes.utm.edu/primes"]The Largest Known Primes Database [/URL] ranked 1st[/B] for Generalized Fermat primes and [B]11th overall[/B].

The discovery was made by [B]Masashi Kumagai[/B] ([URL="http://www.primegrid.com/show_user.php?userid=151189"][B]ragnarag[/B][/URL]) of Japan using an NVIDIA GeForce GTS 450 in an AMD FX(tm)-8150 CPU with 8GB RAM, running 64 bit Windows 7. This GPU took 7 hours 47 minutes to probable prime (PRP) test with GeneferCUDA. Masashi Kumagai is a member of the [B][URL="http://www.primegrid.com/team_display.php?teamid=194"]Team 2ch[/URL][/B] team.

The prime was verified by [B]Jason Preszler[/B] ([B][URL="http://www.primegrid.com/show_user.php?userid=46245"]Jason Preszler[/URL][/B]) of the United States using an Intel Core i7-2600 CPU @ 3.40GHz with 12GB RAM, running 64 bit LINUX . This computer took 46 hours 55 minutes to probable prime (PRP) test with GenefX64. Jason is a member of the [B][URL="http://www.primegrid.com/team_display.php?teamid=1995"]Turan@BOINC[/URL][/B] team.

For more details, please see the [B][URL="http://www.primegrid.com/download/GFN-475856_524288.pdf"]official announcement[/URL][/B].

There's quite a bit of discussion on PG forums how clustered these last three GFNs are. Not unlike the latest Mps.