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 A043505 #15 Apr 24 2021 21:17:49 %S A043505 4,14,24,34,40,41,42,43,45,46,47,48,49,54,64,74,84,94,104,114,124,134, %T A043505 140,141,142,143,145,146,147,148,149,154,164,174,184,194,204,214,224, %U A043505 234,240,241,242,243,245,246,247,248,249,254 %N A043505 Numbers having one 4 in base 10. %H A043505 Enrique Pérez Herrero, <a href="/A043505/b043505.txt">Table of n, a(n) for n = 1..2000</a> %H A043505 <a href="/index/Ar#10-automatic">Index entries for 10-automatic sequences</a>. %t A043505 Select[Range[1000],DigitCount[#,10,4]==1&] (* _Enrique Pérez Herrero_, Nov 29 2013 *) %Y A043505 Cf. A043489, A043493, A043497, A043501, A043509, A043513, A043517, A043521, A043525, A011534. %K A043505 nonn,base %O A043505 1,1 %A A043505 _Clark Kimberling_