A385193 Odd multiplicative orders of 5 modulo primes.

1, 5, 9, 3, 29, 5, 39, 25, 27, 65, 69, 37, 75, 89, 15, 19, 33, 35, 119, 25, 67, 27, 155, 165, 179, 21, 97, 25, 17, 209, 215, 219, 115, 239, 245, 249, 135, 71, 285, 299, 309, 35, 329, 115, 359, 123, 375, 405, 9, 419, 429, 455, 459, 235, 485, 495, 509, 255, 515, 173, 525, 265, 267, 109, 575, 45

Offset

1,2

Comments

a(n) is the multiplicative order of 5 modulo A385192(n).

Odd elements in A211241.

Links

Jianing Song, Table of n, a(n) for n = 1..10000

Example

a(8) = 25 since it is the multiplicative order of 5 modulo A385192(8) = 101, and it is odd.

Mathematica

Select[Map[MultiplicativeOrder[5, #] &, Prime[Range[200]]], OddQ] (* Paolo Xausa, Jun 28 2025 *)

Prog

(PARI) forprime(p=2, 1e4, if(p!=5, z=znorder(Mod(5, p)); if(z%2, print1(z, ", "))))

Crossrefs

Cf. A211241, A385192 (corresponding primes).

Cf. other bases: A139686 (base 2), A385226 (base 3), A385227 (base 4), this sequence (base 5), A385228 (base -2), A385229 (base -3), A385230 (base -4), A385231 (base -5).

Sequence in context: A222074 A388796 A388522 * A245735 A303497 A198990

Adjacent sequences: A385190 A385191 A385192 * A385194 A385195 A385196

Keyword

nonn,easy

Author

Jianing Song, Jun 20 2025

Status

approved