A226746 - OEIS

A226746

Numbers n such that x^2 = 1 has more than two solutions in the Gaussian integers modulo n.

4, 5, 6, 8, 10, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 24, 25, 26, 28, 29, 30, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 44, 45, 46, 48, 50, 51, 52, 53, 54, 55, 56, 57, 58, 60, 61, 62, 63, 64, 65, 66, 68, 69, 70, 72, 73, 74, 75, 76, 77, 78, 80, 82, 84, 85

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..66.

EXAMPLE

13 is in the sequence because 5i, 8i, 1 and 12 are solutions of x^2 = 1 (mod 13).

MATHEMATICA

h[n_] := Flatten[Table[a + b I, {a, 0, n - 1}, {b, 0, n - 1}]]; sol[n_] := Select[h[n], Mod[#^2, n] == 1 &]; Select[Range[100], Length[sol[#]] > 2 &]

CROSSREFS

Sequence in context: A328983 A223133 A295485 * A206416 A144043 A139446

Adjacent sequences: A226743 A226744 A226745 * A226747 A226748 A226749

KEYWORD

nonn

AUTHOR

José María Grau Ribas, Jun 16 2013

STATUS

approved