OFFSET
1,5
COMMENTS
a(790) = -1.
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..10000
PROG
(PARI) a(n) = sum(k=2, n^2-1, (isprime(k)&&k%4==3)-(isprime(k)&&k%4==1));
CROSSREFS
KEYWORD
sign,look
AUTHOR
Seiichi Manyama, Oct 06 2021
STATUS
approved