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 A177916 Numbers k such that k^3 divides 16^(k^2) - 1. 16
 1, 3, 5, 15, 21, 39, 55, 57, 105, 111, 155, 165, 195, 205, 219, 273, 285, 327, 399, 465, 505, 555, 609, 615, 741, 777, 903, 915, 1095, 1155, 1255, 1265, 1365, 1443, 1515, 1533, 1635, 1705, 1995, 2067, 2109, 2145, 2255, 2265, 2289, 2373, 2667, 2715, 2847 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS From Robert Israel, Apr 24 2015: (Start) The only primes in the sequence are 3 and 5. If m and n are in the sequence and are coprime, then m*n is in the sequence. Are all members of the sequence divisible by 3 or 5? (End) LINKS Robert Israel, Table of n, a(n) for n = 1..1000 MAPLE A177916:=n->`if`((16&^(n^2)-1) mod n^3 = 0, n, NULL): seq(A177916(n), n=1..1000); # Wesley Ivan Hurt, Apr 23 2015 MATHEMATICA Select[Range[3000], IntegerQ[(16^(#^2) - 1) / #^3 ] &] (* Vincenzo Librandi, Apr 24 2015 *) PROG (Magma) [n: n in [1..2000] | Denominator((16^(n^2) - 1)/n^3) eq 1]; // Vincenzo Librandi, Apr 24 2015 CROSSREFS Cf. A129211, A129212, A177905, A127106, A177907, A127102, A177909, A177243. Cf. A177911, A177912, A177913, A177914, A177915, A177916, A177917, A177918, A177919, A177920. Sequence in context: A057742 A201433 A101129 * A128396 A155173 A202505 Adjacent sequences: A177913 A177914 A177915 * A177917 A177918 A177919 KEYWORD nonn AUTHOR Alexander Adamchuk, May 14 2010 STATUS approved

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Last modified December 1 18:36 EST 2023. Contains 367500 sequences. (Running on oeis4.)