A366717 Smallest prime dividing 12^n - 1.

11, 11, 11, 5, 11, 7, 11, 5, 11, 11, 11, 5, 11, 11, 11, 5, 11, 7, 11, 5, 11, 11, 11, 5, 11, 11, 11, 5, 11, 7, 11, 5, 11, 11, 11, 5, 11, 11, 11, 5, 11, 7, 11, 5, 11, 11, 11, 5, 11, 11, 11, 5, 11, 7, 11, 5, 11, 11, 11, 5, 11, 11, 11, 5, 11, 7, 11, 5, 11, 11, 11

Offset: 1

Author

Sean A. Irvine, Oct 17 2023

Keywords

• nonn

Comments

Periodic with period 12, repeat of 11, 11, 11, 5, 11, 7, 11, 5, 11, 11, 11, 5.

Crossrefs

Cf. A024140, A366718, A366719.

Programs

Mathematica

Table[FactorInteger[12^n - 1][[1,1]], {n,71}] (* Paul F. Marrero Romero, Oct 25 2023 *)

Formula

a(n) = A020639(A024140(n)). - Paul F. Marrero Romero, Oct 25 2023