20090430, 20:36  #1 
Feb 2003
166_{8} 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
14434_{8} Posts 
Quote:


20090430, 20:48  #3 
Mar 2006
Germany
37×79 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
2·59 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
37×79 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
2^{2}×1,607 Posts 

20101126, 18:41  #9 
Account Deleted
"Tim Sorbera"
Aug 2006
San Antonio, TX USA
2^{2}·11·97 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
3,853 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 

Thread Tools  
Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Search primes of form 2*n^n ± 1  JeppeSN  And now for something completely different  27  20180412 14:20 
Carol / Kynea search (Nearpower primes)  rogue  And now for something completely different  37  20160618 17:58 
MultiFactorial Search  rogue  And now for something completely different  1  20150602 23:51 
Factorial primes  Unregistered  Information & Answers  2  20110911 21:32 
Why Search for these Huge Primes?  Unregistered  Math  8  20050427 00:55 