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 A130433 #29 Feb 16 2025 08:33:06
%S A130433 286,24046,232726,1304446,1707266,2232026,3197806,3922126,4446982,
%T A130433 5603326,5886166,10123366,10169926,12304774,13658086,45133726,
%U A130433 47766286,52249654,62656126,75421126,76254046,91459126,91612246,96956926,108571606,139868326,151513846
%N A130433 Even pseudoprimes to base 3.
%C A130433 The first 27 terms (halved) are given in Table 1 by Paszkiewicz and Rotkiewicz. - _R. J. Mathar_, Aug 22 2012
%H A130433 Amiram Eldar, <a href="/A130433/b130433.txt">Table of n, a(n) for n = 1..215</a> (terms below 10^12, calculated from the b-file at A005935; terms 1..68 from Jeppe Stig Nielsen)
%H A130433 Adam Paszkiewicz and Andrzej Rotkiewicz, <a href="http://tatra.mat.savba.sk/paper.php?id_paper=776">On a Problem of H. J. A. Duprac</a>, Tatra Mt. Math. Publ. 32 (2005) 15-32, MR2206908.
%H A130433 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/FermatPseudoprime.html">Fermat Pseudoprime</a>.
%H A130433 <a href="/index/Ps#pseudoprimes">Index entries for sequences related to pseudoprimes</a>.
%t A130433 Do[ f=PowerMod[ 3, 2n-1, 2n ]; If[ f==1, Print[ 2n ] ], {n,2,7000000} ]
%o A130433 (PARI) forstep(n=4,10^10,2,Mod(3,n)^(n-1)==1 && print1(n,", ")) \\ _Jeppe Stig Nielsen_, Apr 25 2018
%Y A130433 Even terms of A005935.
%Y A130433 Terms of A122780 that are congruent to 2 or 4 modulo 6.
%Y A130433 Cf. A006935, A090082, A090083, A090084, A090085.
%Y A130433 Cf. A130434, A130435, A130436, A130437, A130438, A130439, A130440, A130441, A130442, A130443.
%K A130433 nonn
%O A130433 1,1
%A A130433 _Alexander Adamchuk_, May 26 2007, Jun 17 2007
%E A130433 More terms from _Alexander Adamchuk_, Jun 17 2007
%E A130433 a(25)-a(27) from _Jeppe Stig Nielsen_, Apr 25 2018