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A025020 Numbers whose least quadratic nonresidue (A020649) is 2. 11
3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 15, 16, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 29, 30, 32, 33, 35, 36, 37, 38, 39, 40, 42, 43, 44, 45, 48, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 63, 64, 65, 66, 67, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 81, 83, 84, 85, 86, 87, 88, 90, 91, 92 (list; graph; refs; listen; history; text; internal format)
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[100], Min @ Complement[Range[# - 1], Mod[Range[#/2]^2, #]] == 2 &] (* Amiram Eldar, Oct 31 2020 *)

PROG

(PARI) isA025020(n)={local(r); r=1; for(m=1, n-1, if(m^2%n==2, r=0)); r} \\ Michael B. Porter, Apr 16 2010

CROSSREFS

Cf. A020649, A025021, A025022, A025023, A025024, A025025, A025026, A025027, A025028, A025029.

Sequence in context: A288674 A183294 A039234 * A028974 A184427 A001965

Adjacent sequences:  A025017 A025018 A025019 * A025021 A025022 A025023

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified October 20 10:43 EDT 2021. Contains 348100 sequences. (Running on oeis4.)