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 A177918 Numbers k such that k^3 divides 18^(k^2) - 1. 15
 1, 17, 343927, 1414961, 28626075991, 610559655569, 5417488064959 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS 17 divides a(n) for n > 1. LINKS Table of n, a(n) for n=1..7. MATHEMATICA Select[Range[350000], Mod[PowerMod[18, #^2, #^3] - 1, #^3] == 0 &] (* Julien Kluge, Sep 20 2016 *) 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. Sequence in context: A203677 A099499 A051157 * A297488 A177816 A130653 Adjacent sequences: A177915 A177916 A177917 * A177919 A177920 A177921 KEYWORD hard,more,nonn AUTHOR Alexander Adamchuk, May 14 2010 EXTENSIONS Three more terms from Max Alekseyev, Oct 02 2010 STATUS approved

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Last modified February 21 10:54 EST 2024. Contains 370233 sequences. (Running on oeis4.)