OFFSET
1,2
COMMENTS
Numbers k such that 4*k+1 is a prime or the square of a prime congruent to 3 modulo 4.
If p is a Gaussian prime of norm 4*a(n)+1 (there are two up to association if a(n) is a prime, one if a(n) is the square of a prime), then for any Gaussian integer x, we have x^a(n) == 0, 1, i, -1 or -i (mod p) where i is a primitive fourth root of unity.
LINKS
Jianing Song, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = (A055025(n+1) - 1)/4.
EXAMPLE
2 is a term since 4*2+1 is the norm of the Gaussian prime 3.
PROG
(PARI) isA364868(n) = isA055025(4*n+1) \\ See A055025 for its program
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jianing Song, Aug 11 2023
STATUS
approved