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 A020255 #13 Aug 11 2014 22:45:15 %S A020255 15,91,341,469,871,2257,4371,4411,5149,6097,8401,11581,12431,15577, %T A020255 16471,19093,25681,28009,29539,31417,33001,48133,49141,54913,79003, %U A020255 111361,131773,136741,157651,164737,170431,180571,188191,191351,217801,218791 %N A020255 Strong pseudoprimes to base 29. %H A020255 R. J. Mathar, <a href="/A020255/b020255.txt">Table of n, a(n) for n = 1..688</a> %H A020255 <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a> %K A020255 nonn %O A020255 1,1 %A A020255 _David W. Wilson_