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%I #14 Sep 08 2022 08:46:17
%S 3,11,31,59,71,149,179,191,269,359,389,409,479,569,719,839,1019,1039,
%T 1091,1319,1439,1609,1619,1699,1759,1861,1949,2039,2099,2239,2309,
%U 2459,2579,2621,2749,2819,2879,2909,2939,2999,3119,3229,3449,3461,3581,3709
%N Primes p such that the multiplicative order of 5 modulo p is prime.
%C Odd primes that divide 5^p-1 for some prime p. - _Robert Israel_, Nov 13 2016
%H Robert Israel, <a href="/A277049/b277049.txt">Table of n, a(n) for n = 1..10000</a>
%p select(p -> isprime(p) and isprime(numtheory:-order(5,p)), [3,seq(p,p=7..10000,2)]); # _Robert Israel_, Nov 13 2016
%t Select[Prime@Range@600, PrimeQ@MultiplicativeOrder[5, #] &]
%o (Magma) [p: p in PrimesInInterval(2, 4000) | IsPrime(Modorder(5, p))];
%o (PARI) is(n) = n!=5 && ispseudoprime(n) && ispseudoprime(znorder(Mod(5, n))) \\ _Felix Fröhlich_, Nov 01 2016
%Y Cf. A000040, A277048.
%K nonn
%O 1,1
%A _Vincenzo Librandi_, Oct 28 2016
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