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 A029564 #14 May 21 2013 11:13:53
%S A029564 1886,50711,149171,222101,628421,766931,1105646,1778621,2523902,
%T A029564 5430047,5836181,6265805,9306986,10671881,12450371,21817715,24953666,
%U A029564 32029934,34836791,38697746,48807671,55252571,57264161,63697721,69300086,74157926
%N A029564 Quasi-Carmichael numbers to base -4: squarefree composites n such that prime p|n ==> p+4|n+4.
%H A029564 Giovanni Resta, <a href="/A029564/b029564.txt">Table of n, a(n) for n = 1..541</a> (terms < 10^12)
%H A029564 <a href="/index/Ca#Carmichael">Index entries for sequences related to Carmichael numbers.</a>
%t A029564 qcp[n_, d_] := Block[{p, e}, {p, e} = Transpose@FactorInteger@n;
%t A029564 Length[p] > 1 && Max[e] == 1 && And @@ IntegerQ /@ ((n + d)/(p + d))]; Select[Range[10^6], qcp[#, 4] &] (* _Giovanni Resta_, May 21 2013 *)
%K A029564 nonn
%O A029564 1,1
%A A029564 _David W. Wilson_