cp's OEIS Frontend

A348193 (Number of primes == 3 mod 4 less than n^2) - (number of primes == 1 mod 4 less than n^2).

%I A348193 #17 Oct 07 2021 07:21:31
%S A348193 0,1,1,1,2,2,2,1,3,2,1,3,4,3,5,5,4,3,3,3,2,3,6,6,5,5,6,4,5,5,5,5,6,4,
%T A348193 3,3,4,3,7,12,10,7,10,8,9,10,10,7,6,6,9,8,6,6,9,6,4,9,6,8,8,7,12,11,
%U A348193 11,9,8,9,12,9,12,17,12,13,16,12,16,18,16,15,12,12,11,17,18,14,11,13,9,5,7,7,6,7,8,7,6,8,7,10
%N A348193 (Number of primes == 3 mod 4 less than n^2) - (number of primes == 1 mod 4 less than n^2).
%C A348193 a(790) = -1.
%H A348193 Seiichi Manyama, <a href="/A348193/b348193.txt">Table of n, a(n) for n = 1..10000</a>
%F A348193 a(n) = A348195(n) - A348196(n).
%o A348193 (PARI) a(n) = sum(k=2, n^2-1, (isprime(k)&&k%4==3)-(isprime(k)&&k%4==1));
%Y A348193 Cf. A014085, A077766, A077767, A091295, A348194, A348195, A348196.
%K A348193 sign,look
%O A348193 1,5
%A A348193 _Seiichi Manyama_, Oct 06 2021