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 A218717 #4 Nov 05 2012 12:19:57
%S A218717 0,27,776,153765,6459524,404034898,41865466758,3219884218827,
%T A218717 239822883201307,9110883894036198,991706090146518323,
%U A218717 142813358470363920740,8641533837443707913816,586811715371303018585730,2756887299416274753296336,729513196939063257288876118
%N A218717 a(n) is smallest number such that a(n)^2 + 1 is divisible by 73^n.
%e A218717 a(3) = 153765 because 153765^2+1 = 2 * 73 ^ 3 * 30389.
%t A218717 b=27;n73=73;jo=Join[{0,b},Table[n73=73*n73;b=PowerMod[b,73,n73];b=Min[b,n73-b],{99}]]
%Y A218717 Cf. A002522, A049532, A034939, A218709, A218710, A218712, A218713, A218714, A218715, A218716.
%K A218717 nonn
%O A218717 0,2
%A A218717 _Michel Lagneau_, Nov 04 2012