A025023 Numbers whose least quadratic nonresidue (A020649) is 7.

71, 142, 191, 239, 241, 359, 382, 409, 431, 478, 482, 599, 601, 718, 769, 818, 862, 911, 1031, 1198, 1202, 1249, 1321, 1439, 1489, 1538, 1609, 1822, 1871, 2039, 2062, 2089, 2111, 2161, 2281, 2498, 2591, 2642, 2711, 2878, 2879, 2978, 3001, 3119, 3121, 3169

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[3200], Min @ Complement[Range[# - 1], Mod[Range[#/2]^2, #]] == 7 &] (* 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
isA025023(n)=residue(2, n) && residue(3, n) && residue(5, n) && !residue(7, n) \\ Michael B. Porter, Apr 19 2010
(PARI) is(n)=issquare(Mod(2, n)) && issquare(Mod(3, n)) && issquare(Mod(5, n)) && !issquare(Mod(7, n)) \\ Charles R Greathouse IV, Jan 24 2020

Crossrefs

Cf. A020649, A025020, A025021, A025022, A025024, A025025, A025026, A025027, A025028, A025029.

Sequence in context: A039543 A111092 A140732 * A253016 A157921 A033224

Adjacent sequences: A025020 A025021 A025022 * A025024 A025025 A025026

Keyword

nonn

Author

David W. Wilson

Status

approved