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Re: [PrimeNumbers] Probable 40th Mersenne

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  • Jud McCranie
    ... If you know the divisors then you don t need to sum them - just see if one is 1 and
    Message 1 of 9 , Jun 3, 2003
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      At 06:42 AM 6/3/2003, Jon Perry wrote:

      >Is it not relatively simple to double check whether prime or not - simply
      >add the divisors and see if the result is 2n?

      If you know the divisors then you don't need to sum them - just see if one
      is > 1 and < n.
    • George Woltman
      ... Ernst Mayer is doing a double-check that is expected to complete sometime around the 21st.
      Message 2 of 9 , Jun 3, 2003
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        At 11:42 AM 6/3/2003 +0100, Jon Perry wrote:
        >Still no new news at www.mersenne.org.

        Ernst Mayer is doing a double-check that is expected to complete
        sometime around the 21st.
      • cite13083
        ... simply ... Perhaps you ve confused Mersenne primes with their associated perfect numbers. Exercise: How many proper divisors does the 39th perfect number
        Message 3 of 9 , Jun 11, 2003
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          --- In primenumbers@yahoogroups.com, "Jon Perry" <perry@g...> wrote:
          > Is it not relatively simple to double check whether prime or not -
          simply
          > add the divisors and see if the result is 2n?

          Perhaps you've confused Mersenne primes with their associated perfect
          numbers.

          Exercise: How many proper divisors does the 39th perfect number have?
        • Jon Perry
          Exercise: How many proper divisors does the 39th perfect number have? Impossible to say; http://www.mersenne.org/status.htm Jon Perry perry@globalnet.co.uk
          Message 4 of 9 , Jun 11, 2003
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            'Exercise: How many proper divisors does the 39th perfect number have? '

            Impossible to say;

            http://www.mersenne.org/status.htm

            Jon Perry
            perry@...
            http://www.users.globalnet.co.uk/~perry/maths/
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          • Jack Brennen
            ... Actually, it s impossible to say, but you won t find out why at that link... Nobody knows whether the 39th perfect number is even. Indeed, nobody knows
            Message 5 of 9 , Jun 12, 2003
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              > 'Exercise: How many proper divisors does the 39th perfect number have? '
              >
              > Impossible to say;
              >
              > http://www.mersenne.org/status.htm

              Actually, it's impossible to say, but you won't find out why at
              that link...

              Nobody knows whether the 39th perfect number is even. Indeed, nobody
              knows whether the 19th perfect number is even.

              It would be a safe conjecture that there are no odd perfect numbers,
              but it hasn't been proven. I know that it has been proven that there
              are no odd perfect numbers < 10^300, so certainly the first 12
              perfect numbers are known with certainty.
            • Jon Perry
              I was assuming the no odd perfect conjecture to be true, in the sense that you have assumed it to be false. In which case, it is impossible to say via the
              Message 6 of 9 , Jun 12, 2003
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                I was assuming the 'no odd perfect' conjecture to be true, in the sense that
                you have assumed it to be false. In which case, it is impossible to say via
                the link I gave.

                Jon Perry
                perry@...
                http://www.users.globalnet.co.uk/~perry/maths/
                http://www.users.globalnet.co.uk/~perry/DIVMenu/
                BrainBench MVP for HTML and JavaScript
                http://www.brainbench.com

                -----Original Message-----
                From: Jack Brennen [mailto:jack@...]
                Sent: 12 June 2003 08:14
                To: primenumbers@yahoogroups.com
                Subject: Re: [PrimeNumbers] Re: Probable 40th Mersenne


                > 'Exercise: How many proper divisors does the 39th perfect number have? '
                >
                > Impossible to say;
                >
                > http://www.mersenne.org/status.htm

                Actually, it's impossible to say, but you won't find out why at
                that link...

                Nobody knows whether the 39th perfect number is even. Indeed, nobody
                knows whether the 19th perfect number is even.

                It would be a safe conjecture that there are no odd perfect numbers,
                but it hasn't been proven. I know that it has been proven that there
                are no odd perfect numbers < 10^300, so certainly the first 12
                perfect numbers are known with certainty.





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              • Nathan Russell
                --On Wednesday, June 11, 2003 8:36 PM +0000 cite13083 ... Perfect numbers are never prime - all prime numbers are deficient. This is a pretty stupid way to
                Message 7 of 9 , Jun 12, 2003
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                  --On Wednesday, June 11, 2003 8:36 PM +0000 cite13083
                  <cite13083@...> wrote:

                  > --- In primenumbers@yahoogroups.com, "Jon Perry" <perry@g...> wrote:
                  >> Is it not relatively simple to double check whether prime or not -
                  > simply
                  >> add the divisors and see if the result is 2n?
                  >
                  > Perhaps you've confused Mersenne primes with their associated perfect
                  > numbers.

                  Perfect numbers are never prime - all prime numbers are deficient. This is
                  a pretty stupid way to check for perfect prime numbers - especially since
                  it is likely that all perfect numbers are even, and with an exception even
                  numbers are not prime.

                  > Exercise: How many proper divisors does the 39th perfect number have?

                  I assume you are referring to the 39th known perfect number, which is the
                  39th, or possibly 40th or 41st, even perfect number. The number in
                  question is 2^13466916(2^13466917 - 1)

                  It has 13466917*2-1 proper divisors - we can have any number of factors of
                  2, from 0 to 13466916, either with or without the megaprime. Note that
                  when we have no 2's, and no megaprime, we have the perfectly valid divisor
                  of 1. When we have all possible factors, we have the number itself, thus
                  the -1.

                  As a simpler illustration, take the perfect number 2^2*(2^3-1). It has 2
                  proper divisors with and 3 without the prime
                  2^3-1 - respectively, 1, 2, 4 and 7, 14. Thus the total is 2*3-1 - again,
                  1 less than twice the original exponent.

                  Is this correct?

                  Nathan
                • Jud McCranie
                  ... It is very easy to say about the 39th largest one currently known.
                  Message 8 of 9 , Jun 12, 2003
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                    At 03:33 AM 6/12/2003, Jon Perry wrote:
                    >I was assuming the 'no odd perfect' conjecture to be true, in the sense that
                    >you have assumed it to be false. In which case, it is impossible to say via
                    >the link I gave.

                    It is very easy to say about the 39th largest one currently known.
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