20220111, 09:53  #298 
Aug 2020
79*6581e4;3*2539e3
601 Posts 
New factorial prime
A new factorial prime was recently reported (not yet validated):
288465! + 1 It is very close to the PRPnet search wavefront, is that a coincidence? 
20220118, 23:36  #299 
Sep 2002
Database er0rr
11×389 Posts 
Congrats to PrimeGrid for the "321" prime 3*2^18196595  1 (5,477,722 decimal digits, rank 20)

20220120, 16:54  #300 
Sep 2002
Database er0rr
11·389 Posts 
Sniped again! Congrats to Ryan Propper for the factorial prime 308084! + 1 (1,557,176 decimal digits)

20220120, 17:54  #301 
Aug 2020
79*6581e4;3*2539e3
1131_{8} Posts 
Great to see such progress on the Factorials. Apparently there were so few over the years because few people were working on them. I still think it'd be nice if the work was organized so ranges aren't done twice or thrice, which might well be the case now.

20220120, 20:33  #302 
Jun 2012
Boulder, CO
2·211 Posts 
Don't know who else out there is working on these, but I've sieved (and plan to test) n! ± 1 for 300,000 <= n <= 500,000.

20220201, 22:23  #303 
Jun 2012
Boulder, CO
2×211 Posts 
Update: I've completed testing/doublechecking \(n!1\) and \(n!+1\) for \(150000 \le n \le 330000\) and can confirm the only primes are the 4 known as of Jan 2022:
Code:
308084! + 1 288465! + 1 208003!  1 150209! + 1 
20220201, 22:39  #304  
Sep 2002
Database er0rr
11·389 Posts 
Quote:


20220211, 21:00  #305 
Jun 2012
Boulder, CO
2×211 Posts 
Update: search limit for \(n! ± 1\) is now at \(n=400000\).

20220222, 07:06  #306 
May 2009
Moscow, Russia
B03_{16} Posts 
New factorial prime from Mr. Propper, this will take a while to verify.
Last fiddled with by unconnected on 20220222 at 07:06 
20220316, 15:05  #307  
Jun 2015
Vallejo, CA/.
2·5·113 Posts 
Will there ever be an Official Announcement?
Quote:
Quote:


20220327, 18:25  #308 
Sep 2002
Database er0rr
11·389 Posts 
Another 321 prime!:3 *2^189249881 This one with 5,696,990 and entrance rank 18. So soon after the previous one.

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