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 A029560 #19 Sep 16 2015 01:52:08
%S A029560 35,1295,2635,6083,6923,7315,7843,13363,24335,25795,26243,29795,31003,
%T A029560 43043,44099,49283,50435,54131,115843,138043,147223,191843,234883,
%U A029560 254467,388433,471523,472739,544643,618103,631123,725903,790195,819283,862403
%N A029560 Quasi-Carmichael numbers to base 3: squarefree composites n such that prime p|n ==> p-3|n-3.
%C A029560 Define C(k) to be the numbers n such that n is composite and squarefree and for p prime, p|n => p+k|n+k (p+k and n+k positive); sequence gives C(-3).
%C A029560 These are called 3-Korselt numbers by Bouallegue et al.
%H A029560 Giovanni Resta, <a href="/A029560/b029560.txt">Table of n, a(n) for n = 1..2453</a> (terms < 10^12)
%H A029560 K. Bouallegue, O. Echi, R. G. E. Pinch, <a href="http://dx.doi.org/10.1142/S1793042110002922 ">Korselt numbers and sets</a>, Intl. J. Numb. Theory 6 (2) (2010) 257-269.
%H A029560 <a href="/index/Ca#Carmichael">Index entries for sequences related to Carmichael numbers.</a>
%t A029560 qcm[n_, d_] := Block[{p, e}, {p, e} = Transpose@FactorInteger@n; Length[p] > 1 && Max[e] == 1 && ! MemberQ[p, d] && Max@ Mod[n-d, p-d] == 0]; Select[Range[10^5], qcm[#, 3] &] (* _Giovanni Resta_, May 21 2013 *)
%Y A029560 Cf. A120944
%K A029560 nonn
%O A029560 1,1
%A A029560 _David W. Wilson_