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 A029558 #15 May 21 2013 11:15:30
%S A029558 77,221,2093,3311,8897,10373,33143,35717,48581,52421,54677,61997,
%T A029558 65021,73337,108383,112217,119621,134357,143429,155237,200777,214709,
%U A029558 238901,252197,261749,283871,302789,358853,363263,378437,388841,407813,420893
%N A029558 Quasi-Carmichael numbers to base 5: squarefree composites n such that (n,2*3) = 1 and prime p|n ==> p-5|n-5.
%C A029558 If multiples of 2 and 3 are not excluded, then terms like 21, 1677, 3477, 75621,... belong to the sequence. - _Giovanni Resta_, May 21 2013
%H A029558 Giovanni Resta, <a href="/A029558/b029558.txt">Table of n, a(n) for n = 1..6707</a> (terms < 10^12)
%H A029558 <a href="/index/Ca#Carmichael">Index entries for sequences related to Carmichael numbers.</a>
%t A029558 qcm[n_, d_] := Block[{p, e}, {p, e} = Transpose@FactorInteger@n; Length[p] > 1 && Max[e] == 1 && d < Min[p] && And @@ IntegerQ /@ ((n - d)/(p - d))]; Select[Range[10^6], qcm[#, 5] &] (* _Giovanni Resta_, May 21 2013 *)
%K A029558 nonn
%O A029558 1,1
%A A029558 _David W. Wilson_