A385231 Odd multiplicative orders of -5 modulo primes.

1, 1, 3, 11, 7, 21, 23, 15, 11, 41, 51, 53, 21, 27, 83, 111, 113, 57, 131, 141, 153, 173, 87, 61, 191, 105, 221, 7, 231, 233, 27, 251, 127, 5, 261, 273, 281, 293, 303, 107, 323, 165, 341, 175, 177, 363, 371, 19, 393, 205, 137, 59, 431, 63, 443, 453, 473, 483, 491, 177, 181, 551, 277, 187, 141

Offset

1,3

Comments

Odd elements in A380532.

a(n) is the multiplicative order of -5 modulo A385225(n).

Links

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

Mathematica

Select[Map[MultiplicativeOrder[-5, #] &, Prime[Range[200]]], OddQ] (* Paolo Xausa, Jun 30 2025 *)

Prog

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

Crossrefs

Cf. A380532, A385225 (corresponding primes).

Cf. other bases: A139686 (base 2), A385226 (base 3), A385227 (base 4), A385193 (base 5), A385228 (base -2), A385229 (base -3), A385230 (base -4), this sequence (base -5).

Sequence in context: A164808 A378680 A355895 * A153285 A083557 A119324

Adjacent sequences: A385228 A385229 A385230 * A385232 A385233 A385234

Keyword

nonn,easy

Author

Jianing Song, Jun 22 2025

Status

approved