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A297363
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Numbers k such that (3^ord(3, k) - 1)/k is prime, where ord(3, k) is the multiplicative order of 3 (mod k).
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1
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1, 4, 13, 16, 22, 40, 46, 56, 94, 104, 121, 160, 364, 526, 862, 968, 1093, 1312, 1514, 3146, 3194, 3280, 3742, 4376, 5368, 7280, 7702, 8744, 9841, 28418, 29524, 40880, 69022, 75920, 88573, 106288, 157394
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OFFSET
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1,2
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COMMENTS
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The corresponding primes are 2, 2, 2, 5, 11, 2, 3851, 13, 1001523179, 7, 2, 41, 2, 605199588591144003100881306574406851660288427740394885828171, ...
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LINKS
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Table of n, a(n) for n=1..37.
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EXAMPLE
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46 is in the sequence since ord(3, 46) = 11 and (3^11 - 1)/46 = 3851 is prime.
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MATHEMATICA
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aQ[n_] := PrimeQ[(3^MultiplicativeOrder[3, n] - 1)/n]; Select[ Range[10000], aQ ]
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PROG
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(PARI) isok(n) = (gcd(n, 3) == 1) && isprime((3^znorder(Mod(3, n)) - 1)/n); \\ Michel Marcus, Dec 30 2017
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CROSSREFS
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Cf. A050975, A053446.
Sequence in context: A165336 A031181 A074262 * A031208 A228137 A301965
Adjacent sequences: A297360 A297361 A297362 * A297364 A297365 A297366
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KEYWORD
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nonn,more
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AUTHOR
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Amiram Eldar, Dec 29 2017
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STATUS
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approved
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