20090430, 20:36  #1 
Feb 2003
2·59 Posts 
Factorial primes search?
In case someone is still keeping track of a factorial prime search, all numbers are tested up to 39200.
I looked up various pages (aparently inactive, got them mostly on archive.org) and picked up the last known status for n!+1 and n!1 (it was arround n=37000 with some small ranges completed above that number). Normally I'll get to 40000 for both forms in a few months. If an organized search was still running and someone knows about it, I'd appreciate the info, there is no need to double test right now. Last fiddled with by flava on 20090430 at 20:52 
20090430, 20:43  #2  
"Mark"
Apr 2003
Between here and the
3·29·71 Posts 
Quote:


20090430, 20:48  #3 
Mar 2006
Germany
5462_{8} Posts 
perhaps here: http://fatphil.org/maths/factorial/
there's a file with presieved values: 30000<n<100000 and 30011<p<6320124029 from 2002 Last fiddled with by kar_bon on 20090430 at 20:51 
20090430, 20:51  #4 
Feb 2003
1110110_{2} Posts 
I am aware of that page but the link to the search is dead and the page seems old (not updated since 2002).

20090430, 20:54  #5 
Mar 2006
Germany
2×1,433 Posts 
here is a german current page: http://www.rechenkraft.net/wiki/inde...itle=Primeform

20090430, 21:04  #6 
Feb 2003
2×59 Posts 
Thanks a lot!
Looks like the range I was working on is already done, except the under 39000 ranges marked "in progress". I wonder why I didn't find this page. Probably overlooked it, or it wasn't indexed properly at the time I was looking for a factorial prime search. 
20101126, 14:21  #7 
May 2010
Prime hunting commission.
2^{4}·3·5·7 Posts 
How about k * n! ± 1?
Last fiddled with by 3.14159 on 20101126 at 14:23 
20101126, 15:09  #8 
"Mark"
Apr 2003
Between here and the
6177_{10} Posts 

20101126, 18:41  #9 
Account Deleted
"Tim Sorbera"
Aug 2006
San Antonio, TX USA
10AB_{16} Posts 
Surely an N1/N+1 test could be used with any practical k/n picks?
Last fiddled with by MiniGeek on 20101126 at 18:42 
20101126, 19:30  #10  
Sep 2002
Database er0rr
3,533 Posts 
Quote:


20101127, 13:49  #11  
May 2010
Prime hunting commission.
2^{4}·3·5·7 Posts 
Quote:
Ex: 8717*289!+1. A somewhat larger example; 1085*1950!+1 (5574 digits) There's also k * p(n)# ± 1, if anyone would like; NewPGen can sieve for this type of prime. By the way, (I'm unsure if I asked this before), why is it so difficult to sieve for k * n! ± 1 or k * p(n)# ± 1? Last fiddled with by 3.14159 on 20101127 at 14:12 

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