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 A015904 #11 Oct 23 2018 05:44:57 %S A015904 1,2,3,4,6,12,15,26,28,52,76,78,87,156,364,435,532,988,2356,3052,5356, %T A015904 6916,7588,10095,11476,13636,15051,15964,16458,24388,31996,36114, %U A015904 40132,42484,46396,50428,50726,72436,114846,132652,148276,171076,208468 %N A015904 Numbers k such that k | 12^k + 12. %H A015904 Giovanni Resta, <a href="/A015904/b015904.txt">Table of n, a(n) for n = 1..700</a> %t A015904 Select[Range[10^5], Mod[PowerMod[12, #, #] + 12, #] == 0 &] (* _Giovanni Resta_, Oct 23 2018 *) %Y A015904 Cf. A006517, A015888, A015889, A015891, A015892, A015893, A015897, A015898, A015902, A015903, A015905, A015906. %K A015904 nonn %O A015904 1,2 %A A015904 _Robert G. Wilson v_ %E A015904 Missing a(2)-a(5) from _Giovanni Resta_, Oct 23 2018