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A180744
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Numbers k such that 7^k - 5^k - 1 is prime.
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0
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2, 5, 6, 13, 61, 275, 385, 510, 3559, 9131, 13075, 13829, 28530, 29929
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OFFSET
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1,1
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LINKS
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PROG
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(Magma) [n: n in [0..500]|IsPrime(7^n-5^n-1)];
(PARI) for(n=1, 10000, if(isprime(7^n-5^n-1), print1(n, ", "))); /* Joerg Arndt, May 15 2011 */
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CROSSREFS
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KEYWORD
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nonn,hard,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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