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15704Re: [PrimeNumbers] another way to calculate primes

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  • Gianni Mazzarello
    Dec 6, 2004
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      I noticed I forgot to include 3, it was only distraction.

      However I think this statement is enaugh:

      the set of prime numbers = 2, 3, 5 PLUS all odd numbers > 5, not ending by 5 and not composite.

      7 is included: 7>5, 7 is odd not ending by 5 AND not composite.
      9 is not included: 9 is composite (3^2)
      11 is included: 11>5, 11 is odd not ending by 5 AND not composite.

      By "composite number" I meant an integer that is the product of two or more integers. I hope I used
      the right translation of what I meant.

      Of course we can use a more concise statement:
      pimes = all not composite numbers > 1.
      We will find that, with the exception of 2 and 5, all prime numbers have as final digit one of
      these: 1, 3, 7, 9.


      ----- Original Message -----
      From: "Mary & Graeme" <candlesque@...>
      To: "Mazzarello Gianni" <g.mazzarello@...>
      Sent: Tuesday, December 07, 2004 12:32 AM
      Subject: Re: [PrimeNumbers] another way to calculate primes



      > May I make an observation here?

      >> the set of prime numbers = 2, 5 PLUS all odd numbers > 5, not ending by
      >> 5 and not composite.

      > Might it not be more correct to state:

      > the set of prime numbers = 2,3,5,7,11 PLUS all odd numbers > 5, not ending by
      > 5 and not composite.

      > ... since the first statement would seem to allow 9 as a prime, and omits 3?
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