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 A015888 #21 Mar 31 2024 14:16:58
%S A015888 1,2,3,4,6,12,15,28,366,435,532,804,1036,4636,6364,7932,11476,15051,
%T A015888 19684,40132,75396,80956,247395,266476,280756,307396,356644,490372,
%U A015888 531444,544348,557956,565516,572716,808228,1007574,1256356,1695484
%N A015888 Numbers k such that k | (3^k + 3).
%H A015888 Giovanni Resta, <a href="/A015888/b015888.txt">Table of n, a(n) for n = 1..400</a>
%t A015888 Join[{1,2},Select[Range[17*10^5],PowerMod[3,#,#]==#-3&]] (* _Harvey P. Dale_, Mar 31 2024 *)
%Y A015888 Cf. A006517, A015889, A015891, A015892, A015893, A015897, A015898, A015902, A015903, A015904, A015905, A015906.
%K A015888 nonn
%O A015888 1,2
%A A015888 _Robert G. Wilson v_
%E A015888 Terms 1, 2 inserted by _Max Alekseyev_, Nov 24 2017