OFFSET
1,1
LINKS
Jianing Song, Table of n, a(n) for n = 1..1000
EXAMPLE
781 is a term because 781 = 11*71 is composite, (5/781) = 1, and 5^((781-1)/2) == 1 (mod 781).
7813 is a term because 7813 = 13*601 is composite, (5/7813) = -1, and 5^((7813-1)/2) == -1 (mod 7813).
PROG
(PARI) isA375914(k) = k>1 && !isprime(k) && gcd(k, 10)==1 && Mod(5, k)^((k-1)/2)==kronecker(5, k)
CROSSREFS
| b=2 | b=3 | b=5 |
-----------------------------------+-------------------+---------+----------+
-----------------------------------+-------------------+---------+----------+
-----------------------------------+-------------------+---------+----------+
(b/k)=-1, b^((k-1)/2)==1 (mod k) | | | |
-----------------------------------+-------------------+---------+----------+
(union of first two) | | | |
-----------------------------------+-------------------+---------+----------+
(union of all three) | | | |
KEYWORD
nonn
AUTHOR
Jianing Song, Sep 02 2024
STATUS
approved