A385222 a(n) is the multiplicative order of -10 modulo prime(n); a(1) = a(3) = 0 for completion.

0, 2, 0, 3, 1, 3, 16, 9, 11, 28, 30, 6, 10, 42, 23, 26, 29, 60, 66, 70, 8, 26, 82, 44, 96, 4, 17, 106, 108, 112, 21, 65, 8, 23, 148, 150, 39, 162, 83, 86, 89, 180, 190, 192, 49, 198, 15, 111, 226, 228, 232, 14, 15, 25, 256, 131, 268, 10, 138, 28

Offset

1,2

Links

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

Mathematica

A385222[n_] := If[n == 1 || n == 3, 0, MultiplicativeOrder[-10, Prime[n]]];
Array[A385222, 100] (* Paolo Xausa, Jun 29 2025 *)

Prog

(PARI) a(n, {k=-10}) = my(p = prime(n)); if(k%p==0, 0, znorder(Mod(k, p)))

Crossrefs

Cf. A007348 (primes having primitive root -10).

Cf. bases 2..10: A014664, A062117, A082654, A211241, A211242, A211243, A211244, A211245, A002371.

Cf. bases -2..-10: A337878 (if first term 1), A380482, A380531, A380532, A380533, A380540, A380541, A380542, this sequence.

Sequence in context: A292801 A353396 A396450 * A355533 A355528 A277697

Adjacent sequences: A385219 A385220 A385221 * A385223 A385224 A385225

Keyword

nonn,easy

Author

Jianing Song, Jun 27 2025

Status

approved