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 A044754 #7 May 10 2019 15:36:53
%S A044754 41,141,241,341,419,441,541,641,741,841,941,1041,1141,1241,1341,1419,
%T A044754 1441,1541,1641,1741,1841,1941,2041,2141,2241,2341,2419,2441,2541,
%U A044754 2641,2741,2841,2941,3041,3141,3241,3341,3419,3441
%N A044754 Numbers n such that string 4,1 occurs in the base 10 representation of n but not of n+1.
%t A044754 SequencePosition[Table[If[SequenceCount[IntegerDigits[n],{4,1}]>0,1,0],{n,3500}],{1,0}][[All,1]] (* _Harvey P. Dale_, May 10 2019 *)
%K A044754 nonn,base
%O A044754 1,1
%A A044754 _Clark Kimberling_