

A057762


Numbers n such that 5 is a square mod n.


4



1, 2, 4, 5, 10, 11, 19, 20, 22, 29, 31, 38, 41, 44, 55, 58, 59, 61, 62, 71, 76, 79, 82, 89, 95, 101, 109, 110, 116, 118, 121, 122, 124, 131, 139, 142, 145, 149, 151, 155, 158, 164, 178, 179, 181, 190, 191, 199, 202, 205, 209, 211, 218, 220, 229
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OFFSET

1,2


COMMENTS

Numbers not divisible by 3, 8, or 25 and whose prime factors > 5 are congruent to +/ 1 mod 5.  Eric M. Schmidt, Jan 24 2014


LINKS

T. D. Noe, Table of n, a(n) for n=1..1000


MAPLE

with(numtheory); [seq(mroot(5, 2, p), p=1..400)];


MATHEMATICA

Prepend[ Select[ Range[300], Reduce[ Mod[5  k^2, #] == 0, k, Integers] =!= False &], 1] (* JeanFrançois Alcover, Sep 20 2012 *)
Join[{1, 2, 4, 5}, Select[Range[6, 300], MemberQ[Mod[Range[#]^2, #], 5] &]] (* T. D. Noe, Sep 20 2012 *)


CROSSREFS

Cf. A057126, A057125, A057763.
Sequence in context: A004792 A167795 A138048 * A109511 A018339 A128216
Adjacent sequences: A057759 A057760 A057761 * A057763 A057764 A057765


KEYWORD

nonn


AUTHOR

N. J. A. Sloane, Nov 01 2000


STATUS

approved



