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 A020243 #16 Apr 25 2016 11:45:28
%S A020243 9,91,145,781,1111,2821,4033,4187,5365,5833,6697,7171,15805,19729,
%T A020243 21781,22791,24211,26245,31621,33001,33227,34441,35371,38081,42127,
%U A020243 49771,71071,74665,77293,78881,88831,96433,97921,98671,101101,102311,125563,129493
%N A020243 Strong pseudoprimes to base 17.
%H A020243 R. J. Mathar, <a href="/A020243/b020243.txt">Table of n, a(n) for n = 1..748</a>
%H A020243 <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a>
%o A020243 (PARI) /* with A001262 */
%o A020243 isA020243(n)={ isStrongPsp(n,17) }
%o A020243 { for(n=1,300000000,
%o A020243 if(isA020243(n), print(n) ;) ;
%o A020243 ) ;
%o A020243 } /* R. J. Mathar, Mar 07 2012 */
%Y A020243 Superset of A188755.
%K A020243 nonn
%O A020243 1,1
%A A020243 _David W. Wilson_