A389229 Smallest k for which A388258(k) = n, or -1 if no such k exists.

1, 2, 9, 15, 36, 54, 135, 108, 216, 288, 900, 432, 1152, 1800, 864, 1296, 2700, 1728, 6480, 2592, 5400, 12960, 6912, 5184, 7776, 10800, 10368, 38880, 27648, 15552, 20736, 55296, 57600, 31104, 41472, 46656, 43200, 54000, 62208, 81000, 64800, 144000

Offset

1,2

Links

Table of n, a(n) for n=1..42.

Prog

(Magma) [Min([k: k in [1..3000] | 1 + #[d: d in [1..k-1] | k mod d eq 0 and Modexp(d, d, k) eq -Modexp(-d, k, k) mod k] eq n]): n in [1..18]];
(PARI) a(n) = my(k=1); while (sumdiv(k, d, Mod(d, k)^d == - Mod(-d, k)^k) !=n, k++); k; \\ Michel Marcus, Sep 26 2025

Crossrefs

Cf. A387857, A388258.

Sequence in context: A369154 A108463 A056724 * A295732 A083174 A067547

Adjacent sequences: A389226 A389227 A389228 * A389230 A389231 A389232

Keyword

nonn

Author

Juri-Stepan Gerasimov, Sep 26 2025

Status

approved