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 A130434 #23 Feb 16 2025 08:33:06
%S A130434 6,16806,29234,67798,791578,1234806,1807566,2427706,12562534,29147626,
%T A130434 29783134,38357866,41716918,50167486,99392626,111664666,162474586,
%U A130434 169707826,281780346,286351066,349880326,423200566,463054594,479581642
%N A130434 Even pseudoprimes to base 7.
%H A130434 Amiram Eldar, <a href="/A130434/b130434.txt">Table of n, a(n) for n = 1..163</a> (terms below 10^12, calculated from the b-file at A005938; terms 1..37 from Robert G. Wilson v)
%H A130434 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/FermatPseudoprime.html">Fermat Pseudoprime</a>.
%H A130434 <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a>.
%t A130434 lst = {}; Do[ If[ PowerMod[7, 2n - 1, 2n] == 1, AppendTo[lst, 2n]; Print[2n]], {n, 2, 24000000}]; lst (* _Robert G. Wilson v_, May 28 2007 *)
%Y A130434 Cf. A005938, A006935, A130433, A090082, A090083, A090084, A090085, A130435, A130436, A130437, A130438, A130439, A130440, A130441, A130442, A130443.
%K A130434 nonn
%O A130434 1,1
%A A130434 _Alexander Adamchuk_, May 26 2007
%E A130434 a(9)-a(37) from _Robert G. Wilson v_, May 28 2007