20181230, 06:49  #12  
Dec 2018
2×3 Posts 
Quote:
2^11622415904 took 0.0 seconds to return false because its 1 less than 2^11622415905 and it found a divisor quickly. If I do 2^11622415907 which is 2 (so it stays odd like all primes) it still takes less than a second. 2^11622415905 would take a looooong time to fully calculate. It hasn't returned false after 10 minutes so far...That gives it a higher prime probability! Last fiddled with by Zach010 on 20181230 at 07:06 

20181230, 07:45  #13 
Sep 2002
Database er0rr
F8A_{16} Posts 
Try this number: (2^16603+1)/3. Hint: it has a factor 15585137074585080458129252635718353
or this one: Code:
1296000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000639269244000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000105109353478476000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000005760731904621792049 Code:
6000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000986527 Last fiddled with by paulunderwood on 20181230 at 08:02 
20181230, 08:15  #14  
Dec 2018
6_{16} Posts 
Quote:
Last fiddled with by Zach010 on 20181230 at 08:24 

20181230, 08:32  #15  
Sep 2002
Database er0rr
3978_{10} Posts 
Quote:
The second number I gave is a Carmichael number which passes any Fermat PRP but not certain Lucas tests (although visa versa is possible too with some other numbers), but no one has yet claimed the $620 for a composite number that passes both a (strong) base 2 Fermat PRP test and a (specific) Lucas PRP test i.e. the BPSW test. Last fiddled with by paulunderwood on 20181230 at 08:42 

20181230, 14:40  #16  
Aug 2006
175B_{16} Posts 
Quote:


20181230, 16:42  #17  
"6800 descendent"
Feb 2005
Colorado
2^{4}·43 Posts 
Quote:


20181230, 17:33  #18 
"Curtis"
Feb 2005
Riverside, CA
1421_{16} Posts 
Yes, but you wouldn't use Primo to search for candidates to prove! After one uses some flavor of prp test to find candidates, Primo is the only way for noparticularform numbers of interesting size to go from "it's PRP so I believe it's prime" to "proven prime".

20181230, 19:36  #19  
Einyen
Dec 2003
Denmark
3,253 Posts 
Quote:
But in this forum regarding GIMPS and even most of the side projects going on here, numbers up to 34,987 digits are not very big and are even considered "small", and remember that number took ~2 years on 16 cores to test. Considering more reasonable run times Primo can only test up to ~20K digits. GIMPS new prime and the current wavefront is around 25 million digits! That is NOT ~714 times as large as 34,987 digits but 24965013 orders of magnitude larger! Edit: @PhilF I know you know this, this post was meant for the OP. Last fiddled with by ATH on 20181230 at 19:38 

20181230, 19:50  #20 
"Forget I exist"
Jul 2009
Dumbassville
2^{6}×131 Posts 

20181230, 22:56  #21  
"6800 descendent"
Feb 2005
Colorado
2^{4}·43 Posts 
Quote:


20190111, 05:51  #22 
Aug 2006
3·1,993 Posts 

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