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Thread: How many primes are there of the form 4x+3 less than 100?

  1. Mar 10th 2011, 05:37 AM #1
    sirellwood
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    How many primes are there of the form 4x+3 less than 100?

    Hi,


    How many primes are there of the form less than ?


    Im thinking the answer is 13, but possible it might be 12? depending on whether x=0, prime=3 counts? or maybe neither are right!

    help appreciated!

    Thanks :-)
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  2. Mar 10th 2011, 05:53 AM #2
    roninpro
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    I asked Mathematica, and it gave the list

    3, 7, 11, 19, 23, 31, 43, 47, 59, 67, 71, 79, 83

    which contains 13 primes.
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  3. Mar 10th 2011, 08:44 AM #3
    kira
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    this should help u

    mathforum.org/library/drmath/view/51559.html
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