A025028 Numbers whose least quadratic nonresidue (A020649) is 23.

10559, 15791, 21118, 31582, 50951, 53231, 53881, 88079, 88919, 92569, 97919, 101902, 102001, 106462, 107762, 123191, 128519, 130729, 138311, 142271, 144169, 158759, 166319, 166609, 167879, 173209, 174599, 176158, 176401, 177838, 185138

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• Eric Weisstein's World of Mathematics, Quadratic Nonresidue.

Crossrefs

Cf. A020649, A025020, A025021, A025022, A025023, A025024, A025025, A025026, A025027, A025029.

Programs

PARI

residue(n,m)=local(r);r=0;for(i=1,floor(m/2),if(i^2%m==n,r=1));r
isA025028(n)=local(a);a=1;forprime(p=2,19,a=a && residue(p,n));a=a && !residue(23,n);a \\ Michael B. Porter, Apr 30 2010

PARI

is(n)=forprime(p=2,23, if(!issquare(Mod(p,n)), return(p==23))); 0 \\ Charles R Greathouse IV, Jan 24 2020