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 A020240 #11 Aug 04 2015 05:55:20 %S A020240 15,841,2743,3277,5713,6541,7171,9073,18721,21667,22261,23521,38221, %T A020240 38417,40501,41371,49471,58255,68401,71969,79003,88381,91681,95033, %U A020240 96049,97469,110309,115417,119341,124609,134413,141373,165677,211951,226801 %N A020240 Strong pseudoprimes to base 14. %H A020240 R. J. Mathar, <a href="/A020240/b020240.txt">Table of n, a(n) for n = 1..218</a> %H A020240 <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a> %Y A020240 Cf. A001262 (base 2), A020233 (base 7) %K A020240 nonn %O A020240 1,1 %A A020240 _David W. Wilson_