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Math Help - prime number

  1. #1
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    prime number

    is this possible
    if A is a prime number then A + 100 is also prime is A is not a part of the following series
    2,5,8,11,14,17,20,23,26............
    prove it also
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  2. #2
    MHF Contributor chisigma's Avatar
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    Counterexample: 19 is prime and is not included in the sequence a_{n} = 2+3n, but 119=7\cdot 17 is not a prime...

    Kind regards

    \chi \sigma
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  3. #3
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    leaving 19 ,
    is there a possibility
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  4. #4
    MHF Contributor chisigma's Avatar
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    Further counterexample: 103 \ne 3n-1 is prime, 203 = 7\cdot 29 is not a prime...

    Kind regards

    \chi \sigma
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  5. #5
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    There are over 300 counter examples for numbers less than 10 thousand.
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