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 A083738 #18 Jun 29 2019 08:33:41 %S A083738 1105,2465,10585,18721,29341,46657,75361,104653,115921,162401,226801, %T A083738 252601,278545,294409,314821,334153,340561,399001,410041,449065, %U A083738 488881,512461,530881,534061,552721,574561,658801,721801,852841,1024651 %N A083738 Pseudoprimes to bases 2,3 and 7. %H A083738 Amiram Eldar, <a href="/A083738/b083738.txt">Table of n, a(n) for n = 1..10460</a> (terms 1..98 from R. J. Mathar) %H A083738 F. Richman, <a href="http://math.fau.edu/Richman/carm.htm">Primality testing with Fermat's little theorem</a> %F A083738 a(n) = n-th positive integer k(>1) such that 2^(k-1) = 1 (mod k), 3^(k-1) = 1 (mod k) and 7^(k-1) = 1 (mod k). %e A083738 a(1)=1105 since it is the first number such that 2^(k-1) = 1 (mod k), 3^(k-1) = 1 (mod k) and 7^(k-1) = 1 (mod k). %t A083738 Select[Range[1, 10^5, 2], CompositeQ[#] && PowerMod[2, #-1,#] == PowerMod[3, #-1,#] == PowerMod[7, #-1,#] == 1&] (* _Amiram Eldar_, Jun 29 2019 *) %Y A083738 Intersection of A001567 and A083735. Intersection of A005935 and A083733. - _R. J. Mathar_, Apr 05 2011 %K A083738 easy,nonn %O A083738 1,1 %A A083738 Serhat Sevki Dincer (sevki(AT)ug.bilkent.edu.tr), May 05 2003