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 A020230 #25 Feb 16 2025 08:32:33 %S A020230 341,1387,2047,3277,4033,4371,4681,5461,8321,8911,10261,13747,14491, %T A020230 15709,15841,19951,29341,31621,42799,49141,49981,52633,60787,65077, %U A020230 65281,74665,80581,83333,85489,88357,90751,104653,123251,129921,130561,137149 %N A020230 Strong pseudoprimes to base 4. %H A020230 Amiram Eldar, <a href="/A020230/b020230.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..229 from R. J. Mathar) %H A020230 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/StrongPseudoprime.html">Strong Pseudoprime</a> %H A020230 <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a> %Y A020230 Cf. A020136 (base 4), A001262 (base 2), A020229 (base 3), A020231 (base 5), A020232 (base 6), A020233 (base 7), A020234 (base 8), A020235 (base 9), A020236 (base 10), A020237 (base 11), A020238 (base 12). %K A020230 nonn %O A020230 1,1 %A A020230 _David W. Wilson_