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 A114248 #16 Feb 16 2025 08:32:59
%S A114248 0,0,0,4,11,36,95,257,685,1747,4405,10601,25991,63589,156965,387971,
%T A114248 973753,2471133,6340799
%N A114248 Number of Fermat pseudoprimes to bases 2, 3 and 5 less than 10^n.
%H A114248 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/FermatPseudoprime.html">Fermat Pseudoprime</a>.
%H A114248 <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a>.
%t A114248 Table[Count[Select[Range[2, 10^6], ! PrimeQ[#] && PowerMod[2, # - 1, #] == 1 && PowerMod[3, # - 1, #] == 1 && PowerMod[5, # - 1, #] == 1 &], x_ /; x < 10^n], {n, 6}] (* _Robert Price_, Jun 09 2019 *)
%Y A114248 Cf. A083737.
%K A114248 nonn,more
%O A114248 1,4
%A A114248 _Eric W. Weisstein_, Nov 18 2005
%E A114248 a(9)-a(19) from _Amiram Eldar_, Apr 16 2022