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 A218715 #4 Nov 05 2012 12:19:25
%S A218715 0,23,500,27590,623098,23048345,5041394261,416081467190,
%T A218715 11331029931180,50928660480181,6548598523124085,2441875986594058601,
%U A218715 76594163421571591377,7783548304686046882879,252583670951378815076851,4392422457122810120236558,1165802007767335105471573954
%N A218715 a(n) is smallest number such that a(n)^2 + 1 is divisible by 53^n.
%e A218715 a(3) = 27590 because 27590^2+1 = 53 ^ 3 * 5113.
%t A218715 b=23;n53=53;jo=Join[{0,b},Table[n53=53*n53;b=PowerMod[b,53,n53];b=Min[b,n53-b],{99}]]
%Y A218715 Cf. A002522, A049532, A034939, A218709, A218710, A218712, A218713, A218714.
%K A218715 nonn
%O A218715 0,2
%A A218715 _Michel Lagneau_, Nov 04 2012