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 A044567 #16 Aug 20 2021 13:56:56
%S A044567 48,97,146,195,244,293,342,391,440,489,538,587,636,685,734,783,832,
%T A044567 881,930,979,1028,1077,1126,1175,1224,1273,1322,1371,1420,1469,1518,
%U A044567 1567,1616,1665,1714,1763,1812,1861,1910,1959,2008,2057,2106,2155,2204,2253,2302
%N A044567 Numbers n such that string 6,6 occurs in the base 7 representation of n but not of n+1.
%H A044567 Harvey P. Dale, <a href="/A044567/b044567.txt">Table of n, a(n) for n = 1..1000</a>
%H A044567 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/NonRecursions.html">Non Recursions</a>
%t A044567 SequencePosition[Table[If[SequenceCount[IntegerDigits[n,7],{6,6}]>0,1,0],{n,2500}],{1,0}][[All,1]] (* _Harvey P. Dale_, Aug 20 2021 *)
%Y A044567 Cf. A157362, A010727 [From _Vincenzo Librandi_, Mar 12 2009]
%K A044567 nonn,base
%O A044567 1,1
%A A044567 _Clark Kimberling_
%E A044567 Incorrect Mathematica program deleted by _Harvey P. Dale_, Aug 20 2021