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Math Help - Fermat pseudoprime

  1. #1
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    Fermat pseudoprime

    Last edited by milfner; May 5th 2008 at 09:43 PM.
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  2. #2
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    For the 1st one, its easy to see that 91 = 7 * 13 so its definitely not prime.

    Also 3^{90} = 1mod\ 90 (from observation)

    You can also construct a new pseudoprime N using the proposition:

    Let b >= 2 (where b is the base of this pseudoprime) and p an odd prime where p does not divide b(b-1)(b+1) then

    N = \frac{b^p -1}{b-1}*\frac{b^p+1}{b+1}

    If someone could review this and check for correctness, that would be great!
    Edit: it works fine.
    Last edited by jtsab; May 7th 2008 at 12:37 AM.
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  3. #3
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    Last edited by milfner; May 5th 2008 at 09:43 PM.
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