mersenneforum.org  

Go Back   mersenneforum.org > Great Internet Mersenne Prime Search > Math

Reply
 
Thread Tools
Old 2005-10-04, 15:20   #1
Fredrik
 

227368 Posts
Default Largest random prime

What is the largest prime generated more or less randomly, i.e. not having a particular special form, that has been proven prime with a general-purpose deterministic algorithm?
  Reply With Quote
Old 2005-10-04, 18:44   #2
Numbers
 
Numbers's Avatar
 
Jun 2005
Near Beetlegeuse

22·97 Posts
Default

In 1876, the French mathematician Edouard Lucas proved that 2^(127)-1 was prime. This was at the time the largest known prime number and remains the largest prime found without the aid of a computer.
Ever since then the largest known prime has always had one special form or another, so this number you are looking for is buried somewhere in about (and I’m guessing here) 20 millionth place on the list of the highest primes. Which means that unless someone cared to expend a lot of research time on trying to find it, it is almost certainly anonymous.
If you really, really have to know or you won’t be able to get to sleep, then you might try going here:

http://primes.utm.edu/

Chris Caldwell is widely acknowledged as an authority on this kind of question, and although he does not actively invite queries, he doesn’t bite; but unless he finds it interesting he might just ignore your question.
Numbers is offline   Reply With Quote
Old 2005-10-04, 19:45   #3
Ken_g6
 
Ken_g6's Avatar
 
Jan 2005
Caught in a sieve

5×79 Posts
Default

This page lists the largest primes proven with ECPP, which is a general-purpose primality proving algorithm. That probably means the numbers on that page can't be proven prime because of their special form(s).

The largest one I see on that page that is not described with a special form comes from this page, and is a 7996-digit number.
Ken_g6 is offline   Reply With Quote
Old 2005-10-04, 20:49   #4
jinydu
 
jinydu's Avatar
 
Dec 2003
Hopefully Near M48

175810 Posts
Default

I guess a better way to formulate the question would be:

"What is the largest number to be proven prime using a primality proving algorithm that works for all positive integers?"
jinydu is offline   Reply With Quote
Old 2005-10-05, 03:55   #5
cheesehead
 
cheesehead's Avatar
 
"Richard B. Woods"
Aug 2002
Wisconsin USA

170148 Posts
Default

Quote:
Originally Posted by jinydu
"What is the largest number to be proven prime using a primality proving algorithm that works for all positive integers
... but on which no known primality proving algorithm that requires a special form can be used
Quote:
?"
cheesehead is offline   Reply With Quote
Old 2005-10-12, 14:43   #6
fatphil
 
fatphil's Avatar
 
May 2003

3×7×11 Posts
Default

Quote:
Originally Posted by Fredrik
What is the largest prime generated more or less randomly, i.e. not having a particular special form, that has been proven prime with a general-purpose deterministic algorithm?
Some have called these "entropic" primes. Ones for which no uniquely defining description can be shorter than just the number itself. The current, but perhaps invalid, record is held by David Broadhurst, but claims to invalidity were based on the fact that I believed that his numbers could possibly be compressed marginally (by a few bits out of several hundred thousand).

Unfortunately there's not really anything mathematically interesting about such numbers. Two calls to a random number generator are all you need, one to chose a factor for BLS/KP/CHG, and one to decide where to search for primes. Dirichlet guarantees there'll be something eventually.
fatphil is offline   Reply With Quote
Reply



Similar Threads
Thread Thread Starter Forum Replies Last Post
(M48) NEW MERSENNE PRIME! LARGEST PRIME NUMBER DISCOVERED! dabaichi News 571 2020-10-26 11:02
odds of random number being prime jasong jasong 32 2009-12-01 06:43
Odds that a random number is prime Number theory Homework Help 4 2009-08-28 22:04
Odds of a prime number being random Orgasmic Troll Lounge 6 2007-08-11 04:09
need Pentium 4s for 5th largest prime search (largest proth) wfgarnett3 Lounge 7 2002-11-25 06:34

All times are UTC. The time now is 15:03.


Mon Aug 2 15:03:57 UTC 2021 up 10 days, 9:32, 0 users, load averages: 3.26, 3.17, 3.32

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.