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A116621 Positive integers n such that 13^n == 1 (mod n). 21
1, 2, 3, 4, 6, 8, 9, 12, 14, 16, 18, 20, 24, 27, 28, 32, 36, 40, 42, 48, 54, 56, 60, 64, 68, 72, 80, 81, 84, 96, 98, 100, 108, 112, 120, 126, 128, 136, 140, 144, 160, 162, 168, 180, 183, 192, 196, 200, 204, 216, 220, 224, 240, 243, 252, 256, 272, 280, 288, 294, 300, 320 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..10000 (terms 1..1000 from G. C. Greubel)

MATHEMATICA

Join[{1}, Select[Range[1, 750], Mod[13^#, #] == 1 &]] (* G. C. Greubel, Nov 19 2017 *)

Join[{1}, Select[Range[320], PowerMod[13, #, #] == 1 &]] (* Robert Price, Apr 10 2020 *)

PROG

(PARI) isok(n) = Mod(13, n)^n == 1; \\ Michel Marcus, Nov 19 2017

CROSSREFS

Column k=13 of A333432.

Cf. A116609, A116611, A116620.

Sequence in context: A232966 A331728 A113961 * A036407 A145807 A278962

Adjacent sequences:  A116618 A116619 A116620 * A116622 A116623 A116624

KEYWORD

nonn

AUTHOR

Zak Seidov, Feb 19 2006

EXTENSIONS

1 prepended by Max Alekseyev, Jun 28 2011

STATUS

approved

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Last modified June 18 19:58 EDT 2021. Contains 345121 sequences. (Running on oeis4.)