A128403 Numbers k such that k^2 divides 23^k-1.

1, 2, 4, 6, 8, 11, 12, 20, 22, 24, 40, 42, 44, 60, 66, 78, 84, 88, 120, 132, 156, 168, 212, 220, 264, 312, 420, 424, 440, 444, 462, 474, 546, 620, 636, 660, 780, 820, 840, 858, 888, 924, 948, 1014, 1060, 1092, 1218, 1220, 1240, 1272, 1320, 1560, 1640, 1716

Offset: 1

Author

Alexander Adamchuk, Mar 01 2007

Keywords

• nonn
• less

Links

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

Crossrefs

Cf. A127103, A127104, A127105, A127106, A127107, A127102, A127101, A127100, A127092, A128405, A128393, A128394, A128395, A128396, A128397, A128398, A128399, A128400, A128401, A128402, A128404.

Programs

Mathematica

Join[{1},Select[Range[2000],PowerMod[23,#,#^2]==1&]] (* Harvey P. Dale, May 02 2015 *)