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 A043507 #14 Apr 24 2021 21:16:15 %S A043507 444,1444,2444,3444,4044,4144,4244,4344,4404,4414,4424,4434,4440,4441, %T A043507 4442,4443,4445,4446,4447,4448,4449,4454,4464,4474,4484,4494,4544, %U A043507 4644,4744,4844,4944,5444,6444,7444,8444,9444,10444 %N A043507 Numbers having three 4's in base 10. %H A043507 Daniel Starodubtsev, <a href="/A043507/b043507.txt">Table of n, a(n) for n = 1..10000</a> %t A043507 Select[Range[11000],DigitCount[#,10,4]==3&] (* _Harvey P. Dale_, Aug 17 2020 *) %Y A043507 Subsequence of A011534. %K A043507 nonn,base %O A043507 1,1 %A A043507 _Clark Kimberling_