A366718 Largest prime factor of 12^n - 1.

11, 13, 157, 29, 22621, 157, 4943, 233, 80749, 22621, 266981089, 20593, 20369233, 13063, 22621, 260753, 74876782031, 80749, 29043636306420266077, 85403261, 8177824843189, 57154490053, 321218438243, 2227777, 12629757106815551, 20369233, 86769286104133

Offset: 1

Author

Sean A. Irvine, Oct 17 2023

Keywords

• nonn

Links

• Max Alekseyev, Table of n, a(n) for n = 1..310
• J. Brillhart et al., Factorizations of b^n +- 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.

Crossrefs

Cf. A024140, A006530, A005420, A074477, A274906, A074479, A274907, A074249, A274908, A274909, A005422, A274910, A366707, A366708, A366709, A366710, A366711, A366717, A366720.

Programs

Magma

[Maximum(PrimeDivisors(12^n-1)): n in [1..40]];

Mathematica

Table[FactorInteger[12^n - 1][[-1, 1]], {n, 40}]

Formula

a(n) = A006530(A024140(n)).