%I #21 Jan 20 2024 16:39:39
%S 1,1,5,20,73,248,745,1954,5239,13837,36042,92893
%N Number of Fermat pseudoprimes to base 5 less than 10^n.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/FermatPseudoprime.html">Fermat Pseudoprime</a>
%H <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a>
%t Table[Count[Select[Range[2, 10^6], ! PrimeQ[#] && PowerMod[5, # - 1, #] == 1 &], x_ /; x < 10^n], {n, 6}] (* _Robert Price_, Jun 09 2019 *)
%Y Cf. A005936, A114245, A114249.
%K nonn,more
%O 1,3
%A _Eric W. Weisstein_, Nov 18 2005
%E a(9)-a(12) from _Hiroaki Yamanouchi_, Sep 25 2015