A067946 Numbers k that divide 5^k - 1.

1, 2, 4, 6, 8, 12, 16, 18, 24, 32, 36, 42, 48, 52, 54, 64, 72, 84, 96, 104, 108, 126, 128, 144, 156, 162, 168, 186, 192, 208, 216, 252, 256, 272, 288, 294, 312, 324, 336, 342, 372, 378, 384, 416, 432, 468, 486, 504, 512, 544, 558, 576, 588, 624, 648, 672, 676

Offset: 1

Author

Benoit Cloitre, Mar 05 2002

Keywords

• easy
• nonn

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A024049.

Programs

Mathematica

Join[{1},Select[Range[700],PowerMod[5,#,#]==1&]] (* Harvey P. Dale, Feb 25 2015 *)

PARI

is(n)=Mod(5,n)^n==1 \\ Charles R Greathouse IV, Nov 04 2016