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A025027 Numbers whose least quadratic nonresidue (A020649) is 19. 10
5711, 9239, 10391, 10799, 11422, 14951, 18478, 20782, 21598, 29902, 33049, 34319, 36599, 37489, 40031, 42719, 44641, 49009, 49921, 51769, 53089, 55441, 57119, 59929, 61151, 61871, 63361, 66098, 67369, 67679, 68638, 69001, 71569, 73198, 74978, 75479 (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[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

Cf. A020649, A025020, A025021, A025022, A025023, A025024, A025025, A025026, A025028, A025029.

Sequence in context: A235207 A252342 A237743 * A030469 A244163 A253423

Adjacent sequences:  A025024 A025025 A025026 * A025028 A025029 A025030

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified May 14 12:17 EDT 2021. Contains 343882 sequences. (Running on oeis4.)