New factorial prime
 

A new factorial prime was [URL="https://primes.utm.edu/primes/page.php?id=133139"]recently reported[/URL] (not yet validated):

288465! + 1

It is very close to the PRPnet search wavefront, is that a coincidence?

Congrats to PrimeGrid for the [URL="https://primes.utm.edu/primes/page.php?id=133193"]"321" prime 3*2^18196595 - 1[/URL] (5,477,722 decimal digits, rank 20) :banana:

Sniped again! Congrats to Ryan Propper for the [URL="https://primes.utm.edu/primes/page.php?id=133196"]factorial prime 308084! + 1[/URL] (1,557,176 decimal digits) :banana:

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.

[QUOTE=bur;598421]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.[/QUOTE]

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.

Update: I've completed testing/double-checking [$]n!-1[/$] and [$]n!+1[/$] for [$]150000 \le n \le 330000[/$] and can confirm the only primes are the 4 [URL="https://primes.utm.edu/top20/page.php?id=30"]known[/URL] as of Jan 2022:

[CODE]308084! + 1
288465! + 1
208003! - 1
150209! + 1[/CODE]

Continuing on up to [$]n=500000[/$].

[QUOTE=ryanp;599226]Update: I've completed testing/double-checking [$]n!-1[/$] and [$]n!+1[/$] for [$]150000 \le n \le 330000[/$] and can confirm the only primes are the 4 [URL="https://primes.utm.edu/top20/page.php?id=30"]known[/URL] as of Jan 2022:

[CODE]308084! + 1
288465! + 1
208003! - 1
150209! + 1[/CODE]

Continuing on up to [$]n=500000[/$].[/QUOTE]

I suppose that PrimeGrid's factorial sub-project is defunct now, unless they start at n=500000 :wink:

Update: search limit for [$]n! ± 1[/$] is now at [$]n=400000[/$].

New [URL="https://primes.utm.edu/primes/page.php?id=133604"]factorial prime[/URL] from Mr. Propper, this will take a while to verify.

Will there ever be an Official Announcement?
 

[QUOTE=paulunderwood;598299]Congrats to PrimeGrid for the [URL="https://primes.utm.edu/primes/page.php?id=133193"]"321" prime 3*2^18196595 - 1[/URL] (5,477,722 decimal digits, rank 20) :banana:[/QUOTE]

.
[QUOTE]6 3*2^18196595-1 5,477,722 (decimal) vaclav_m (primes) BOINC@Poland 2022-01-08 20:46:05 UTC T5K [C]No official Announcement[/C] 321 Prime Search 217,652.558[/QUOTE]

Another [URL="https://primes.utm.edu/primes/page.php?id=133776"]321- prime![/URL]:3 *2^18924988-1 This one with 5,696,990 and entrance rank 18. So soon after the previous one. :smile: