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 A020287 #13 Aug 04 2015 06:51:42 %S A020287 15,217,341,1261,2701,3661,6541,6697,7613,13213,16213,22177,23653, %T A020287 23959,31417,50117,61777,63139,67721,76301,77421,79381,80041,102341, %U A020287 113491,115231,145993,160147,163073,164737,170941,178709,197209,210817,249631 %N A020287 Strong pseudoprimes to base 61. %C A020287 The smallest number which is a strong pseudoprime to the bases 2 (A001262), 7 (A020233) and also 61 (here) is 4759123141 [Jaeschke]. - R. J. Mathar, Apr 05 2011 %H A020287 R. J. Mathar, <a href="/A020287/b020287.txt">Table of n, a(n) for n = 1..202</a> %H A020287 G. Jaeschke, <a href="http://dx.doi.org/10.1090/S0025-5718-1993-1192971-8">On strong pseudoprimes to several bases</a>, Mathematics of Computation, 61 (1993), 915-926. %H A020287 <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a> %K A020287 nonn %O A020287 1,1 %A A020287 _David W. Wilson_