A277048 - OEIS

%I #17 Sep 08 2022 08:46:17

%S 11,13,23,47,59,83,107,167,179,227,263,347,359,383,431,467,479,503,

%T 563,587,683,719,839,863,887,983,1019,1091,1093,1187,1223,1283,1307,

%U 1319,1367,1439,1487,1511,1523,1583,1597,1619,1669,1823,1871,1907,2027

%N Primes p such that the multiplicative order of 3 modulo p is prime.

%C Odd primes that divide 3^p-1 for some prime p. - _Robert Israel_, Nov 14 2016

%H Robert Israel, <a href="/A277048/b277048.txt">Table of n, a(n) for n = 1..10000</a>

%p select(p -> isprime(p) and isprime(numtheory:-order(3, p)), [seq(p, p=5..10000, 2)]); # _Robert Israel_, Nov 14 2016

%t Select[Prime@ Range@ 310, PrimeQ@ MultiplicativeOrder[3, #] &] (* _Michael De Vlieger_, Oct 28 2016 *)

%o (Magma) [p: p in PrimesInInterval(2, 4000) | IsPrime(Modorder(3, p))];

%o (PARI) isok(n) = isprime(n) && isprime(znorder(Mod(3,n))); \\ _Michel Marcus_, Oct 28 2016

%Y Cf. A000040, A122094.

%K nonn

%O 1,1

%A _Vincenzo Librandi_, Oct 28 2016