login
A129497
Composite numbers k such that 7^k (mod k) is a power of 7 greater than 1.
6
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
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
KEYWORD
easy,nonn
AUTHOR
Robert G. Wilson v, Apr 17 2007
EXTENSIONS
Corrected and edited by R. J. Mathar, May 16 2008
STATUS
approved