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 A128155 #6 Oct 02 2013 15:12:55
%S A128155 2,13,6,11,10,533,218,119,12,145,214,57,106,17149,17,3736136819,26,
%T A128155 117,206,143,34,427,202,871,40,25397,54,6877,52,115,194,6839309,48,
%U A128155 4857103,38,63,94,94043,62,95,46,303,182,121214771,55,1137417899,178,3327,116
%N A128155 a(n) = least k such that the remainder when 15^k is divided by k is n.
%H A128155 Robert G. Wilson v, <a href="/A128155/a128155.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 A128155 t = Table[0, {10000} ]; k = 1; While[ k < 3000000000, a = PowerMod[15, k, k]; If[a < 10001 && t[[a]] == 0, t[[a]] = k; Print[{a, k}]]; k++ ]; t
%Y A128155 Cf. A036236, A078457, A119678, A119679, A127816, A119715, A119714, A127817, A127818, A127819, A127820, A127821, A128154, A128156, A128157, A128158, A128159, A128160, A128149, A128150.
%K A128155 hard,nonn
%O A128155 1,1
%A A128155 _Alexander Adamchuk_, Feb 16 2007
%E A128155 More terms from _Ryan Propper_, Feb 28 2007