OFFSET
1,1
COMMENTS
For a prime p congruent to 1 mod 16, the number 2 is an octavic residue mod p if and only if there are integers x and y such that x^2 + 256*y^2 = p.
LINKS
Arkadiusz Wesolowski, Table of n, a(n) for n = 1..10000
PROG
(Magma) [p: p in PrimesUpTo(12577) | p mod 16 eq 1 and exists(t){x : x in ResidueClassRing(p) | x^8 eq 2}]; // Arkadiusz Wesolowski, Dec 19 2020
(PARI) isok(p) = isprime(p) && (Mod(p, 16) == 1) && ispower(Mod(2, p), 8); \\ Michel Marcus, Dec 19 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Arkadiusz Wesolowski, Dec 16 2014
STATUS
approved