This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A177905 #11 Jun 06 2021 09:03:43
%S A177905 1,2,4,6,12,26,42,52,68,78,84,114,156,186,204,222,228,372,444,546,798,
%T A177905 876,884,1092,1218,1252,1302,1378,1428,1482,1554,1596,1806,2418,2436,
%U A177905 2604,2652,2756,2886,2964,3108,3534,3606,3612,3756,3876,4134,4218,4836
%N A177905 Numbers k such that k^3 divides 5^(k^2) - 1.
%H A177905 Harvey P. Dale, <a href="/A177905/b177905.txt">Table of n, a(n) for n = 1..900</a>
%p A177905 A177905:=n->`if`(5^(n^2)-1 mod n^3 = 0, n, NULL): seq(A177905(n), n=1..10^3); # _Wesley Ivan Hurt_, Feb 16 2017
%t A177905 Join[{1},Select[Range[5000],PowerMod[5,#^2,#^3]==1&]] (* _Harvey P. Dale_, May 04 2017 *)
%Y A177905 Cf. A067946 (k divides 5^k-1), A127105 (k^2 divides 5^k-1).
%Y A177905 Cf. A129211, A129212, A177905, A127106, A177907, A127102, A177909, A177243.
%Y A177905 Cf. A177911, A177912, A177913, A177914, A177915, A177916, A177917, A177918, A177919, A177920.
%K A177905 nonn
%O A177905 1,2
%A A177905 _Alexander Adamchuk_, May 14 2010