%I #11 Aug 04 2015 06:26:06
%S 21,671,889,1891,2059,2761,5461,7999,13051,15311,16441,21667,25681,
%T 34861,37901,38989,42127,49771,50737,54811,64681,68251,78961,85591,
%U 88831,92509,93031,96049,97921,105001,109061,111361,114841,123713,143009,145351
%N Strong pseudoprimes to base 20.
%H R. J. Mathar, <a href="/A020246/b020246.txt">Table of n, a(n) for n = 1..208</a>
%H <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a>
%K nonn
%O 1,1
%A _David W. Wilson_