OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Quadratic Nonresidue.
MATHEMATICA
Select[Range[20000], Min @ Complement[Range[# - 1], Mod[Range[#/2]^2, #]] == 19 &] (* Amiram Eldar, Oct 31 2020 *)
PROG
(PARI) residue(n, m)=local(r); r=0; for(i=1, floor(m/2), if(i^2%m==n, r=1)); r
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
(PARI) is(n)=forprime(p=2, 19, if(!issquare(Mod(p, n)), return(p==19))); 0 \\ Charles R Greathouse IV, Jan 24 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved