A129497 Composite numbers k such that 7^k (mod k) is a power of 7 greater than 1.

14, 21, 25, 42, 50, 56, 58, 62, 70, 74, 82, 84, 86, 94, 98, 105, 106, 112, 118, 122, 132, 133, 134, 142, 146, 147, 150, 152, 158, 166, 168, 178, 182, 194, 196, 202, 206, 210, 214, 218, 226, 231, 254, 262, 266, 274, 278, 294, 298, 301, 302, 314, 325, 326, 334

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

58 is a member of the sequence since 7^58 (mod 58) == 49.

Mathematica

Select[Range@ 335, (p = PowerMod[7, #, #]) > 1 && IntegerQ@ Log[7, p] && CompositeQ[#] &] (* corrected by Amiram Eldar, Jul 24 2021 *)

Crossrefs

Cf. A036236, A129492, A129493, A129494, A129495, A129496.

Sequence in context: A162780 A002410 A108606 * A255742 A093994 A114985

Adjacent sequences: A129494 A129495 A129496 * A129498 A129499 A129500

Keyword

easy,nonn

Author

Robert G. Wilson v, Apr 17 2007

Extensions

Corrected and edited by R. J. Mathar, May 16 2008

Status

approved