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A273946
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Odd prime factors of generalized Fermat numbers of the form 5^(2^m) + 1 with m >= 0.
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8
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3, 13, 17, 257, 313, 641, 769, 2593, 11489, 19457, 65537, 163841, 786433, 1503233, 1655809, 7340033, 14155777, 18395137, 23606273, 29423041, 39714817, 75068993, 167772161, 2483027969, 4643094529, 6616514561, 47148957697, 241931001601, 2748779069441
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OFFSET
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1,1
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COMMENTS
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Odd primes p such that the multiplicative order of 5 (mod p) is a power of 2.
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REFERENCES
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Hans Riesel, Common prime factors of the numbers A_n=a^(2^n)+1, BIT 9 (1969), pp. 264-269.
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LINKS
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MATHEMATICA
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Select[Prime@Range[2, 10^5], IntegerQ@Log[2, MultiplicativeOrder[5, #]] &]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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