%I #18 Mar 01 2022 20:28:19
%S 2047,15841,104653,1004653,10323769,100463443,1002261781,10000321321,
%T 100004790097,1000002977551,10000130243671,100002236680837,
%U 1000003918690669,10000008250001701,100000150553089531,1000000274500018837,10000003599249373469
%N a(n) is the smallest n-digit strong pseudoprime (in base 2).
%H Patrick De Geest, <a href="http://www.worldofnumbers.com/won125.htm">Smallest n-digit pseudoprimes (base 2)</a>
%H <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a>
%e a(1)=2047 because 2047 is the smallest 4-digit strong pseudoprime to base 2.
%Y Cf. A001567, A068216, A067845, A001262, A062852.
%K hard,base,nonn
%O 4,1
%A _Shyam Sunder Gupta_, Feb 13 2002
%E Edited by _Charles R Greathouse IV_, Nov 01 2009
%E a(17)-a(20) from _Charles R Greathouse IV_, Mar 14 2011
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