Stories
Slash Boxes
Comments
typodupeerror delete not in

Hot Comments

Comments: 47 +-   45th and 46th Mersenne Primes Confirmed on Saturday September 13 2008, @02:58PM

Posted by kdawson on Saturday September 13 2008, @02:58PM
from the interest-rate dept.
math
science
kahunak writes to alert us that GIMPS has announced that the 45th and 46th Mersenne primes have been confirmed. The EFF's $100,000 award, for the first prime over 10 million digits in length, will probably be claimed. (We discussed no. 45 when it was announced.)
story

Related Stories

This discussion has been archived. No new comments can be posted.
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
 Full
 Abbreviated
 Hidden
More
Loading... please wait.
        • Re:Prime Post! (Score:5, Interesting)

          by QuickFox (311231) on Saturday September 13 2008, @04:08PM (#24993315)

          Not quite. In fact I will hereby reveal to the world the exact beginning and the exact ending of the 47th Mersenne prime (not just the 45th or the 46th, really the 47th!) as written in binary notation.

          Not kidding, dead serious, this is the real thing:

          11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 ... ... ... 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111 11111111

          Mersenne numbers are by definition 2^n-1, which means that in binary notation every such number is a sequence of ones.

          • Re: (Score:2, Interesting)

            Infinity of Mersenne primes isn't proven, you'll have to post the whole thing for us to believe you.
            • True, but it would be strange that there would be a limited amount of Mersenne primes using un unlimited amount of primes. But this could be the case. Still, we are at millions of digits now and we have 2 new ones so I am guessing that there are infinite.

          • Mersenne numbers are by definition 2^n-1, which means that in binary notation every such number is a sequence of ones.

            Since the length of the number in base-10 is a little more than 10 million digits, and 10^3 is roughly 2^10, does this mean n is as low as 33-35 million?

            • Re: (Score:3, Interesting)

              Mersenne numbers are by definition 2^n-1, which means that in binary notation every such number is a sequence of ones.

              Since the length of the number in base-10 is a little more than 10 million digits, and 10^3 is roughly 2^10, does this mean n is as low as 33-35 million?

              Nevermind, checked Wikipedia. The largest currently known n is 32,582,657 so apparently my reasoning is correct.

    • Re: (Score:1, Flamebait)

      (#24992811)

      Prime factors:

      3
      2776979

      fail

      • (#24992811)

        Prime factors:

        3 2776979

        UID.

        fail

        Sweet Christ, you managed to not only be wrong, but at the same time un-ironically use an awful 4chan meme to do it.

        • first: he was talking about the post not his UID

          second:

          His UID factors into

          109 4127(semiprime)

          you fail

          troll

      • He wasn't talking about any of that crap. He says "Prime Post" because his post is the second comment on THIS ARTICLE (a play on the First Post meme). 2 is, obviously, a prime. Are people just that oblivious, or am I the oblivious one not realizing that Mr. Daimanta and Mr. 19thNervousBreakdown here are trolling?
        • How the hell can he predict whether his post is the second one or not? Unless you struck a deal with /. admins or omniscient you can never know. But somehow you are capable of convienently forgetting this fact.

          troll

  • Well, last week I discovered the prime number 37. It was only a matter of time before I discovered one greater than 10 million digits.

    Now these show-offs have gone ahead and spoiled it for the rest of us.
  • by RAMMS+EIN (578166) on Saturday September 13 2008, @03:20PM (#24992909) Homepage Journal

    Not knowing why Mersenne primes matter, I looked it up on The Ultimate Source Of Truth [wikipedia.org]. From The Fine Article [wikipedia.org]:

    Many fundamental questions about Mersenne primes remain unresolved. It is not even known whether there is a largest Mersenne prime, which would mean that the set of Mersenne primes is finite. The Lenstra-Pomerance-Wagstaff conjecture asserts that, on the contrary, there are infinitely many Mersenne primes and predicts their order of growth. It is also not known whether infinitely many Mersenne numbers with prime exponents are composite, although this would follow from widely believed conjectures about prime numbers, for example, the infinitude of Sophie Germain primes.

    Mersenne primes are used in pseudorandom number generators such as Mersenne Twister and ParkMiller RNG.

    Mersenne primes were considered already by Euclid, who found a connection with the perfect numbers.

    Mersenne numbers are very good test cases for the special number field sieve algorithm

    Out of those, I only knew about the connection with pseudorandom number generators, which I became interested in after writing my deadbeef random number generator [inglorion.net].

    • by l2718 (514756) on Saturday September 13 2008, @04:11PM (#24993335)
      I think this tell us a lot more about the potential power of distributed computing than about prime numbers. While Mersenne primes are interesting to number theorists, we'll never find enough to do statistics on -- they are mostly of interests to pure mathematicians for reasons of curiosity. Random prime numbers of about 1024 bits are much more useful (and easier to find). On the other hand, if these was ever a problem we really needed to solve (protein-folding screensavers come to mind) then we now know how much computation power we can harness.
      • by kevinatilusa (620125) <kcostell&gmail,com> on Saturday September 13 2008, @11:35PM (#24995981)

        Knowledge of whether or not there are infinitely many Mersenne primes would probably not be interesting even to most pure mathematicians -- it's sort of a bizarre question that seems disconnected from the rest of mathematics. What would be interesting would be the actual methods used to prove this. In practice almost every question involving the existence/non-existence of certain types of primes is one we already know the answer to.

        The reason for this lies in the prime number theorem, which says that the proportion of numbers less than N which are prime is about 1/Log(N). Unless there's some compelling reason to believe otherwise, you can guess the answer to many problems involving primes by replacing them with a set randomly chosen with the same probability.

        For example, a randomly chosen number near 2^p-1 will be prime with probability about proportional to 1/p. Since the sum of 1/p diverges, we expect there to be infinitely many Mersenne primes (and can even guess their number, though this requires a bit more careful analysis to take care of the observation that Mersenne numbers don't have small prime factors, but this should only increase their number).

        The same trick allows us to guess the answer for twin primes (sum diverges, so there should be infinitely many) and Fermat primes (primes of the form 2^(2^n)+1 -- the sum converges, so there should be only finitely many). But none of these are really rigorous proofs, because they're all based on the fundamental assumption that the primes are somehow pseudorandom.

        Depending on the method of attack, a proof of the infinitude of Mersenne Primes may also shed light on how accurate or inaccurate the pseudorandomness assumption is. I would consider that to be a VERY interesting question.

  • by the_humeister (922869) on Saturday September 13 2008, @04:16PM (#24993375)
    ... because they coincidentally correspond to two of Britney Spears's songs encoded as mp3 files at 128kb and the RIAA won't allow such copyright infringement! Double ouch!
    • Re: (Score:2, Insightful)

      ... because they coincidentally correspond to two of Britney Spears's songs encoded as mp3 files at 128kb and the RIAA won't allow such copyright infringement! Double ouch!

      If that's the case, no great loss, we wouldn't want to see (or hear) them anyway!

    • This just in: Britney Spears is actually a weapon sent by aliens to enslave the Earth through hidden prime number telepathic messages.

      News at eleven.

    • I don't think even the RIAA is sick enough to enforce copyright infringement on Britney's songs. I mean anyone *THAT* sick to download em is capable of much more hideous actions and even the RIAA is scared of some things.
  • Well that suxs for Bruce [geekz.co.uk]. Now he has to change the combination on his luggage again.
Barometer, n.: An ingenious instrument which indicates what kind of weather we are having. -- Ambrose Bierce, "The Devil's Dictionary"