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Old 2022-01-11, 09:53   #298
bur
 
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79*6581e-4;3*2539e-3

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Default 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?
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Old 2022-01-18, 23:36   #299
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Congrats to PrimeGrid for the "321" prime 3*2^18196595 - 1 (5,477,722 decimal digits, rank 20)
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Old 2022-01-20, 16:54   #300
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Sniped again! Congrats to Ryan Propper for the factorial prime 308084! + 1 (1,557,176 decimal digits)
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Old 2022-01-20, 17:54   #301
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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.
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Old 2022-01-20, 20:33   #302
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Quote:
Originally Posted by bur View Post
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.
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.
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Old 2022-02-01, 22:23   #303
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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 known as of Jan 2022:

Code:
308084! + 1
288465! + 1
208003! - 1
150209! + 1
Continuing on up to \(n=500000\).
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Old 2022-02-01, 22:39   #304
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Quote:
Originally Posted by ryanp View Post
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 known as of Jan 2022:

Code:
308084! + 1
288465! + 1
208003! - 1
150209! + 1
Continuing on up to \(n=500000\).
I suppose that PrimeGrid's factorial sub-project is defunct now, unless they start at n=500000
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Old 2022-02-11, 21:00   #305
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Update: search limit for \(n! ± 1\) is now at \(n=400000\).
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Old 2022-02-22, 07:06   #306
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New factorial prime from Mr. Propper, this will take a while to verify.

Last fiddled with by unconnected on 2022-02-22 at 07:06
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Old 2022-03-16, 15:05   #307
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Default Will there ever be an Official Announcement?

Quote:
Originally Posted by paulunderwood View Post
Congrats to PrimeGrid for the "321" prime 3*2^18196595 - 1 (5,477,722 decimal digits, rank 20)
.
Quote:
6 3*2^18196595-1 5,477,722 (decimal) vaclav_m (primes) BOINC@Poland 2022-01-08 20:46:05 UTC T5K No official Announcement 321 Prime Search 217,652.558
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Old 2022-03-27, 18:25   #308
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Another 321- prime!:3 *2^18924988-1 This one with 5,696,990 and entrance rank 18. So soon after the previous one.
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