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%I #15 Oct 31 2020 04:35:41
%S 5711,9239,10391,10799,11422,14951,18478,20782,21598,29902,33049,
%T 34319,36599,37489,40031,42719,44641,49009,49921,51769,53089,55441,
%U 57119,59929,61151,61871,63361,66098,67369,67679,68638,69001,71569,73198,74978,75479
%N Numbers whose least quadratic nonresidue (A020649) is 19.
%H Amiram Eldar, <a href="/A025027/b025027.txt">Table of n, a(n) for n = 1..10000</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/QuadraticNonresidue.html">Quadratic Nonresidue</a>.
%t Select[Range[20000], Min @ Complement[Range[# - 1], Mod[Range[#/2]^2, #]] == 19 &] (* _Amiram Eldar_, Oct 31 2020 *)
%o (PARI) residue(n,m)=local(r);r=0;for(i=1,floor(m/2),if(i^2%m==n,r=1));r
%o isA025027(n)=local(a);a=1;forprime(p=2,17,a=a && residue(p,n));a=a && !residue(19,n);a \\ _Michael B. Porter_, Apr 30 2010
%o (PARI) is(n)=forprime(p=2,19, if(!issquare(Mod(p,n)), return(p==19))); 0 \\ _Charles R Greathouse IV_, Jan 24 2020
%Y Cf. A020649, A025020, A025021, A025022, A025023, A025024, A025025, A025026, A025028, A025029.
%K nonn
%O 1,1
%A _David W. Wilson_
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