20170214, 21:41  #67  
"Marian Otremba"
Jan 2017
Kielcza, Poland
11 Posts 
Quote:
The list of all multifactorial primes I have tested by myself is included in the file: http://mfprimes.republika.pl/Range_m...an_otremba.txt I have also added your new results that were missing in mine and Kevin's data. IMHO the results on my page are complete. Right now I am searching multifactorial primes (n!k+1) with digits <= 10,000 and k = 102..200 

20170214, 21:47  #68  
"Marian Otremba"
Jan 2017
Kielcza, Poland
1011_{2} Posts 
Quote:
I verified this result Primality testing 559741!7+1 [N1, BrillhartLehmerSelfridge] Running N1 test using base 79967 Calling BrillhartLehmerSelfridge with factored part 33.95% 559741!7+1 is prime! (4675.2281s+2.1494s) (digits 424902) Mark Rodenkirch 02/2017 OK Last fiddled with by chroma on 20170214 at 21:51 

20170215, 00:42  #69 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
2·3·1,657 Posts 

20170215, 03:31  #70  
"Mark"
Apr 2003
Between here and the
6,737 Posts 
Quote:
It is not submitted to UTM because this is not owned by me (even though it has my name) and I need to add mfsieve to it. Chris hasn't responded to me yet. 

20170215, 04:06  #71  
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
2×3×1,657 Posts 
Quote:
__ __ __ __ __ __ Re: first question. Clearly, x!_{m} 1 has strong implications on the survivor values of x (mod m) after sieving with small primes. Take m=2, for example. Can x be odd and x!_{2} 1 prime? Clearly not (except for trivial 1!_{2} + 1 and 3!_{2}  1, where both equal two 2, obviously. All other even numbers are not prime.). Now, because x must be even, for the rest of the sieve, you get only (2x)!_{2} 1,which is equal to x! * 2^{x} 1 which doesn't require an explanation what "!_{2}" or "!!" exactly is. Well, almost everyone knows what "!" means without an explanation. So, my question was about the same for m=7. And because you have the sieve file, I expected just simple stats, not a theory. (Apparently I can exclude x=1 (mod 7) for the "1" form.) But that's ok; I left the m=7 sieve running and will have a look at my own copy of the sieve file tomorrow morning... 

20170215, 13:40  #73 
"Mark"
Apr 2003
Between here and the
6,737 Posts 

20170216, 11:02  #74  
"Marian Otremba"
Jan 2017
Kielcza, Poland
B_{16} Posts 
Quote:
n > (35 = 5*7, 49 = 7^2, 147 = 3*7^2, 336 = 2^4*3*7, 2079 = 3^3*7*11, 8855 = 5*7*11*23, 20636 = 2^2*7*11*67, 22988 = 2^2*7*821, 41139 = 3^2*7*653, 208502 = 2*7*53*281, 559741 = 7*13*6151) and for mfp1 (n!71) n > (14 = 2*7, 98 = 2*7^2, 371 = 7*53, 959 = 7*137, 4389 = 3*7*11*19, 10150 = 2*5^2*7*29, 13321 = 7*11*173, 54481 = 7*43*181, 61467 = 3*7*2927, 92288 = 2^7*7*103, 330925 = 5^2*7*31*61, 368851 = 7*23*29*79, 446236 = 2^2*7*15937) Last fiddled with by chroma on 20170216 at 11:04 

20170305, 21:18  #75 
"Marian Otremba"
Jan 2017
Kielcza, Poland
B_{16} Posts 
A new record of largest multifactorial primes
220502!2+1 is prime! (digits: 541,239) SFukui 01/2017 http://primes.utm.edu/primes/page.php?id=122753 
20170305, 21:26  #76  
"Mark"
Apr 2003
Between here and the
6,737 Posts 
Quote:


20170312, 13:34  #77 
"Mark"
Apr 2003
Between here and the
6,737 Posts 
FYI, I updated the first post to redirect to Marian's page.

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