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 A029569 #14 May 21 2013 11:11:34
%S A029569 231,2679,18471,24311,61171,71799,84271,107371,112871,140151,150071,
%T A029569 305359,364791,420391,483351,854845,948631,966671,1003191,1209745,
%U A029569 1260791,1327911,1451791,1675511,1691351,1870167,1982391,2400935,2721535
%N A029569 Quasi-Carmichael numbers to base -9: squarefree composites n such that prime p|n ==> p+9|n+9.
%H A029569 Giovanni Resta, <a href="/A029569/b029569.txt">Table of n, a(n) for n = 1..2185</a> (terms < 10^12)
%H A029569 <a href="/index/Ca#Carmichael">Index entries for sequences related to Carmichael numbers.</a>
%t A029569 qcp[n_, d_] := Block[{p, e}, {p, e} = Transpose@FactorInteger@n;
%t A029569 Length[p] > 1 && Max[e] == 1 && And @@ IntegerQ /@ ((n + d)/(p + d))]; Select[Range[10^6], qcp[#, 9] &] (* _Giovanni Resta_, May 21 2013 *)
%K A029569 nonn
%O A029569 1,1
%A A029569 _David W. Wilson_