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 A020238 #18 Nov 17 2019 09:33:33 %S A020238 91,133,145,247,1649,1729,2821,8911,9073,10585,13051,13333,16471, %T A020238 19517,20737,21361,24013,24727,26467,29539,31483,31621,34219,34861, %U A020238 35881,38311,38503,40321,53083,67861,79381,79501,88831,97351,115231,121301,131977 %N A020238 Strong pseudoprimes to base 12. %H A020238 Amiram Eldar, <a href="/A020238/b020238.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..210 from R. J. Mathar) %H A020238 <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a> %Y A020238 Cf. A020140, A001262 (base 2), A020229 (base 3), A020230, A020231, A020232, A020233, A020234, A020235, A020236, A020237. %K A020238 nonn %O A020238 1,1 %A A020238 _David W. Wilson_