A129495 Composite numbers k such that 5^k (mod k) is a power of 5 greater than 1.

10, 15, 20, 26, 30, 34, 38, 40, 46, 50, 56, 58, 60, 62, 65, 74, 78, 82, 86, 94, 100, 106, 118, 120, 122, 124, 129, 130, 132, 134, 140, 141, 142, 143, 146, 150, 155, 158, 159, 166, 177, 178, 182, 183, 190, 194, 195, 200, 201, 202, 206, 213, 214, 217, 218, 219

Offset

1,1

Links

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

Example

26 is a member of the sequence since 5^26 (mod 26) == 25.

Mathematica

Select[Range@ 225, (p = PowerMod[5, #, #]) > 1 && IntegerQ@ Log[5, p] && CompositeQ[#] &] (* corrected by Amiram Eldar, Jul 24 2021 *)

Crossrefs

Cf. A036236, A129492, A129493, A129494, A129496, A129497.

Sequence in context: A284804 A006623 A035166 * A101258 A344330 A091418

Adjacent sequences: A129492 A129493 A129494 * A129496 A129497 A129498

Keyword

easy,nonn

Author

Robert G. Wilson v, Apr 17 2007

Status

approved