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A297363 Numbers n such that (3^ord(3, n) - 1)/n is prime, where ord(3, n) is the multiplicative order of 3 (mod n). 0
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The corresponding primes are 2, 2, 2, 5, 11, 2, 3851, 13, 1001523179, 7, 2, 41, 2, 605199588591144003100881306574406851660288427740394885828171, ...

LINKS

Table of n, a(n) for n=1..37.

EXAMPLE

46 is in the sequence since ord(3, 46) = 11 and (3^11 - 1)/46 = 3851 is prime.

MATHEMATICA

aQ[n_] := PrimeQ[(3^MultiplicativeOrder[3, n] - 1)/n]; Select[ Range[10000], aQ ]

PROG

(PARI) isok(n) = (gcd(n, 3) == 1) && isprime((3^znorder(Mod(3, n)) - 1)/n); \\ Michel Marcus, Dec 30 2017

CROSSREFS

Cf. A050975, A053446.

Sequence in context: A165336 A031181 A074262 * A031208 A228137 A301965

Adjacent sequences:  A297360 A297361 A297362 * A297364 A297365 A297366

KEYWORD

nonn,more

AUTHOR

Amiram Eldar, Dec 29 2017

STATUS

approved

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Last modified April 22 06:01 EDT 2021. Contains 343161 sequences. (Running on oeis4.)