OFFSET
1,1
COMMENTS
Odd primes that divide 5^p-1 for some prime p. - Robert Israel, Nov 13 2016
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
select(p -> isprime(p) and isprime(numtheory:-order(5, p)), [3, seq(p, p=7..10000, 2)]); # Robert Israel, Nov 13 2016
MATHEMATICA
Select[Prime@Range@600, PrimeQ@MultiplicativeOrder[5, #] &]
PROG
(Magma) [p: p in PrimesInInterval(2, 4000) | IsPrime(Modorder(5, p))];
(PARI) is(n) = n!=5 && ispseudoprime(n) && ispseudoprime(znorder(Mod(5, n))) \\ Felix Fröhlich, Nov 01 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, Oct 28 2016
STATUS
approved