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%I #21 Feb 23 2023 11:36:34
%S 1,2,6,16,73,234,659,1797,4950,13070,33989,87448
%N Number of Fermat pseudoprimes to base 7 less than 10^n.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/FermatPseudoprime.html">Fermat Pseudoprime</a>
%t Table[Count[Select[Range[2, 10^6], ! PrimeQ[#] && PowerMod[7, # - 1, #] == 1 &], x_ /; x < 10^n], {n, 6}] (* _Robert Price_, Jun 09 2019 *)
%Y Cf. A005938, A055550, A114245, A114247.
%K nonn,more
%O 1,2
%A _Eric W. Weisstein_, Nov 18 2005
%E a(9)-a(12) from _Hiroaki Yamanouchi_, Sep 25 2015