A177918 Numbers k such that k^3 divides 18^(k^2) - 1.

1, 17, 343927, 1414961, 28626075991, 610559655569, 5417488064959

Offset: 1

Author

Alexander Adamchuk, May 14 2010

Keywords

• hard
• more
• nonn

Comments

17 divides a(n) for n > 1.

Crossrefs

Cf. A128358 (k divides 18^k - 1), A128398 (k^2 divides 18^k - 1).

Cf. A129211, A129212, A177905, A127106, A177907, A127102, A177909, A177243.

Cf. A177911, A177912, A177913, A177914, A177915, A177916, A177917, A177918, A177919, A177920.

Programs

Mathematica

Select[Range[350000], Mod[PowerMod[18, #^2, #^3] - 1, #^3] == 0 &] (* Julien Kluge, Sep 20 2016 *)

Extensions

Three more terms from Max Alekseyev, Oct 02 2010