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 A128368 #8 Aug 01 2015 04:50:17
%S A128368 3,13,5,6,23,11,15,194,19,18,17,148,213,22,131209,20,2335,25,7311,44,
%T A128368 259,51,5263,38,21927,758,240055,29,803,58,21921,55,4405,39,413,316,
%U A128368 549,746,17831,62,4367,106,165,74,19253,82,6455,88,147,734,62093,122
%N A128368 a(n) = least k such that the remainder when 28^k is divided by k is n.
%H A128368 Robert G. Wilson v, <a href="/A128368/a128368.txt">Table of n, a(n) for n = 1..10000 with -1 for large entries where a(n) has not yet been found</a>
%t A128368 t = Table[0, {10000} ]; k = 1; While[ k < 5000000000, a = PowerMod[28, k, k]; If[a < 10001 && t[[a]] == 0, t[[a]] = k; Print[{a, k}]]; k++ ]; t (* _Robert G. Wilson v_, Aug 06 2009 *)
%Y A128368 Cf. A128361, A128362, A128363, A128364, A128365, A128366, A128367, A128369, A129370, A128371, A128372.
%Y A128368 Cf. A036236, A078457, A119678, A119679, A127816, A119715, A119714, A127817, A127818, A127819, A127820, A127821, A128154, A128155, A128156, A128157, A128158, A128159, A128160.
%Y A128368 Cf. A128149, A128150, A128172.
%K A128368 hard,nonn
%O A128368 1,1
%A A128368 _Alexander Adamchuk_, Feb 27 2007