A387370 Smallest k for which A386310(k) = n, or -1 if no such k exists.

1, 2, 8, 18, 64, 54, 162, 144, 216, 288, 1458, 432, 8748, 1152, 864, 1296, 4608, 1728, 9216, 2592, 3456, 51200, 6912, 5184, 7776, 13824, 27000, 10368, 27648, 15552, 20736, 32400, 256000, 69984, 31104, 43200, 4718592, 221184, 62208, 64800, 139968, 86400, 165888, 124416, 108000

Offset

1,2

Links

Robert G. Wilson v, Table of n, a(n) for n = 1..121

Mathematica

a[n_]:=Module[{k=0}, Until[Length[Select[Divisors[k], PowerMod[#, #, k] == Mod[k - PowerMod[#, #, k], k] &]]==n, k++]; k]; Array[a, 36] (* James C. McMahon, Sep 05 2025 *)

Prog

(PARI) f(n) = sumdiv(n, d, #select(x->(x==2), digits(d))); \\ A387394
a(n) = my(k=1); while(f(k) !=n, k++); k; \\ Michel Marcus, Aug 30 2025

Crossrefs

Cf. A386310.

Sequence in context: A058082 A005675 A054358 * A268658 A074128 A376114

Adjacent sequences: A387367 A387368 A387369 * A387371 A387372 A387373

Keyword

nonn

Author

Juri-Stepan Gerasimov, Aug 27 2025

Extensions

More terms from Michel Marcus, Aug 30 2025

Status

approved