A332021 - OEIS

%I #16 Feb 07 2020 11:44:19

%S 2,3,6,7,8,10,11,13,15,18,21,24,26,27,28,32,33,39,41,44,45,48,50,52,

%T 54,55,56,58,60,62,65,68,69,71,74,75,79,83,84,85,88,90,93,95,101,107,

%U 108,109,110,114,116,117,118,119,120,122,123,124,126,129,130,131,133,135,139

%N Elements of the set {m > 0: m is a quadratic nonresidue modulo prime(m)}.

%C This is the complement sequence of A332020.

%C The conjecture in A332020 implies that the number of terms not exceeding x is about x/2 asymptotically.

%H Zhi-Wei Sun, <a href="/A332021/b332021.txt">Table of n, a(n) for n = 1..10000</a>

%e a(1) = 2 since 2 is a quadratic nonresidue modulo prime(2) = 3.

%e a(2) = 3 since 3 is a quadratic nonresidue modulo prime(3) = 5.

%t tab = {}; Do[If[JacobiSymbol[n, Prime[n]] == -1, tab = Append[tab, n]], {n, 140}]; tab

%o (PARI) isok(m) = kronecker(m, prime(m)) !=1; \\ _Michel Marcus_, Feb 06 2020

%Y Cf. A000040, A000290, A242750, A332020.

%K nonn

%O 1,1

%A _Zhi-Wei Sun_, Feb 04 2020