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Math Help - Composite numbers

  1. #1
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    Composite numbers

    I've read in somewhere that f_{n} = 2^{2^{n}}+1 is never prime for all integers n>4. How can that be proven?
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  2. #2
    Senior Member
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    Dec 2007
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    Anchorage, AK
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    Whether there are any Fermat numbers F_n, n>4, that are prime is an unsolved question in mathematics; see here.

    --Kevin C.
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