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Prime number

  1. Sep 17, 2006 #1
    Hi I have difficulty to begin with this problem:

    prove or disapprove that 2n-1 is prime for all non negative integers n.

    I know the definition of a prime number but how to apply it for this proof?

    Please, can I have a suggestion to start this problem?

  2. jcsd
  3. Sep 17, 2006 #2


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    Homework Helper

    Try some values of n and see if you can find a composite number (hint: I wouldn't be telling you to do this unless your search would end eventually).
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