A387364 Least number which is not a prime power and whose prime factors are equal modulo n.

6, 15, 10, 21, 14, 55, 46, 33, 22, 39, 26, 85, 82, 51, 34, 57, 38, 115, 118, 69, 46, 141, 142, 145, 159, 87, 58, 93, 62, 259, 314, 185, 202, 111, 74, 205, 226, 123, 82, 129, 86, 235, 262, 141, 94, 371, 291, 265, 298, 159, 106, 321, 327, 295, 334, 177, 118, 183

Offset

1,1

Links

Robert G. Wilson v, Table of n, a(n) for n = 1..10000

Example

For n = 2, factors of a(2) = 15 are 3 and 5, they both have a residue of 1 mod 2.

Mathematica

a[n_]:=Module[{k=1}, Until[!PrimePowerQ[k]&&Min[Mod[First/@FactorInteger[k], n]]==Max[Mod[First/@FactorInteger[k], n]], k++]; k]; Array[a, 58] (* James C. McMahon, Sep 03 2025 *)

Prog

(PARI) f(k, n) = if (!isprimepower(k), my(f=factor(k)[, 1]); #Set(apply(x->Mod(x, n), f)) == 1);
a(n) = my(k=1); while (!f(k, n), k++); k; \\ Michel Marcus, Aug 27 2025

Crossrefs

First term of A380758 when n = 10.

Sequence in context: A381805 A389358 A215739 * A161397 A145257 A245200

Adjacent sequences: A387361 A387362 A387363 * A387365 A387366 A387367

Keyword

nonn

Author

Yaroslav Deryavko, Aug 27 2025

Status

approved