A116621 Positive integers n such that 13^n == 1 (mod n).

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

Offset: 1

Author

Zak Seidov, Feb 19 2006

Keywords

• nonn

Links

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

Crossrefs

Column k=13 of A333432.

Cf. A116609, A116611, A116620.

Programs

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 *)

PARI

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

Extensions

1 prepended by Max Alekseyev, Jun 28 2011