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A081763
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Primes p such that p*(p-1) divides 3^(p-1)-1.
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1
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2, 5, 17, 41, 101, 257, 401, 641, 881, 1361, 1601, 2441, 3089, 4001, 5441, 5501, 6101, 12101, 13121, 13421, 14081, 14741, 15101, 16001, 18041, 20201, 25301, 25601, 29921, 30881, 32801, 35201, 39041, 39161, 40961, 49409, 53681, 54401, 54449
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OFFSET
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1,1
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COMMENTS
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All terms == 2 (mod 3). Also most are congruent to 1 (mod 10). Those that are not: 2, 5, 17, 257, 3089, 49409, 54449, 65537, 83969, 149057, .... - Robert G. Wilson v, Dec 02 2013
Number of terms < 10^k: 2, 4, 9, 17, 49, 105, 244, 574, 1388, .... - Robert G. Wilson v, Dec 02 2013
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LINKS
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MATHEMATICA
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Select[ Prime@ Range@ 6000, PowerMod[3, # - 1, # (# - 1)] == 1 &] (* Robert G. Wilson v, Dec 02 2013 *)
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PROG
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(PARI) lista(nn) = forprime(p=2, nn, if (! ((3^(p-1)-1) % (p*(p-1))), print1(p, ", "))) \\ Michel Marcus, Dec 02 2013
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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