A262931 Numbers k such that 6 is a square mod k.

1, 2, 3, 5, 6, 10, 15, 19, 23, 25, 29, 30, 38, 43, 46, 47, 50, 53, 57, 58, 67, 69, 71, 73, 75, 86, 87, 94, 95, 97, 101, 106, 114, 115, 125, 129, 134, 138, 139, 141, 142, 145, 146, 149, 150, 159, 163, 167, 173, 174, 190, 191, 193, 194, 197, 201, 202, 211, 213

Offset

1,2

Links

Alois P. Heinz, Table of n, a(n) for n = 1..20000

Example

6^2 == 6 (mod 15), so 15 is a term.

Maple

with(numtheory):
a:= proc(n) option remember; local k;
      for k from 1+`if`(n=1, 0, a(n-1))
      while mroot(6, 2, k)=FAIL do od; k
    end:
seq(a(n), n=1..80);  # Alois P. Heinz, Feb 24 2017

Mathematica

Join[{1}, Table[If[Reduce[x^2 == 6, Modulus->n] === False, Null, n], {n, 2, 300}]//Union] (* Vincenzo Librandi, Oct 05 2015 *)

Prog

(PARI) for(n=1, 300, if (issquare(Mod(6, n)), print1(n", "))); \\ Altug Alkan, Oct 04 2015
(Magma) [n: n in [1..300] | exists(t){x : x in ResidueClassRing(n) | x^2 eq 6}]; // Vincenzo Librandi, Oct 05 2015

Crossrefs

Cf. A057125, A057126, A057762, A262932.

Sequence in context: A039848 A018494 A101475 * A018524 A057035 A243805

Adjacent sequences: A262928 A262929 A262930 * A262932 A262933 A262934

Keyword

nonn,easy

Author

Erik Pelttari, Oct 04 2015

Status

approved