OFFSET
1,1
COMMENTS
Primes p such that q = (p-1)/2 is composite, 3^q == 1 (mod p) and 3^(q-1) == 1 (mod p-1).
All terms == 5 (mod 6).
LINKS
Robert Israel, Table of n, a(n) for n = 1..212
EXAMPLE
p = 3083 is in the sequence because it is prime, q = (3083-1)/2 = 23*67 is composite, 3^q == 1 (mod p) and 3^(q-1) == 1 mod (p-1).
MAPLE
filter:= p -> isprime(p) and not isprime((p-1)/2) and
3&^((p-3)/2) mod (p-1) = 1 and
3 &^((p-1)/2) mod p = 1;
select(filter, [seq(p, p=5..10^7, 6)]); # Robert Israel, Mar 31 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert Israel, Mar 31 2017
STATUS
approved