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 A105573 #12 Feb 06 2020 15:20:00
%S A105573 20,136,200,224,344,346,368,376,480,488,554,568,576,640,736,744,808,
%T A105573 816,854,856,864,872,880,944,992,1064,1152,1160,1200,1208,1214,1216,
%U A105573 1280,1288,1312,1360,1426,1568,1576,1606,1621,1648,1656,1664,1784,1808,1858
%N A105573 Numbers m such that m-4 and m+4 have 4 prime factors.
%C A105573 A001222(a(n)-4) = A001222(a(n)+4) = 4.
%C A105573 Prime factors counted with multiplicity. - _Harvey P. Dale_, Feb 06 2020
%H A105573 Harvey P. Dale, <a href="/A105573/b105573.txt">Table of n, a(n) for n = 1..1000</a>
%e A105573 1214 - 4 = 1210 = 2 * 5 * 11 * 11 and 1214 + 4 = 1218 = 2 * 3 * 7 * 29 so 1214 is in the sequence. - _Jon E. Schoenfield_, Jan 19 2015
%t A105573 q=4;lst={};Do[If[Plus@@Last/@FactorInteger[n-q]==q&&Plus@@Last/@FactorInteger[n+q]==q,AppendTo[lst,n]],{n,7!}];lst (* _Vladimir Joseph Stephan Orlovsky_, Feb 01 2009 *)
%t A105573 Mean/@SequencePosition[PrimeOmega[Range[2000]],{4,_,_,_,_,_,_,_,4}] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Feb 06 2020 *)
%Y A105573 Cf. A014574, A105571, A105572.
%K A105573 nonn
%O A105573 1,1
%A A105573 _Reinhard Zumkeller_, Apr 14 2005