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A025025 Least non-residue mod n is 13. 0
479, 958, 1151, 1319, 2302, 2351, 2638, 2689, 3529, 3671, 3911, 4702, 4751, 4919, 5378, 5519, 5569, 6599, 7058, 7342, 7559, 7561, 7681, 7822, 8951, 9241, 9502, 9601, 9719, 9769, 9838, 11038, 11138, 12049, 12239, 12721, 12911, 13151, 13198, 14159 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..40.

PROG

(PARI) residue(n, m)=local(r); r=0; for(i=1, floor(m/2), if(i^2%m==n, r=1)); r

isA025025(n)=local(a); a=1; forprime(p=2, 11, a=a && residue(p, n)); a=a && !residue(13, n); a \\ Michael B. Porter, Apr 30 2010

(PARI) is(n)=issquare(Mod(2, n)) && issquare(Mod(3, n)) && issquare(Mod(5, n)) && issquare(Mod(7, n)) && issquare(Mod(11, n)) && !issquare(Mod(13, n)) \\ Charles R Greathouse IV, Jan 24 2020

CROSSREFS

Sequence in context: A186950 A056987 A323051 * A108256 A262222 A115157

Adjacent sequences:  A025022 A025023 A025024 * A025026 A025027 A025028

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified May 26 00:32 EDT 2020. Contains 334613 sequences. (Running on oeis4.)