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 A043508 #21 Apr 24 2021 21:13:23 %S A043508 4444,14444,24444,34444,40444,41444,42444,43444,44044,44144,44244, %T A043508 44344,44404,44414,44424,44434,44440,44441,44442,44443,44445,44446, %U A043508 44447,44448,44449,44454,44464,44474,44484,44494,44544 %N A043508 Numbers having four 4's in base 10. %H A043508 Daniel Starodubtsev, <a href="/A043508/b043508.txt">Table of n, a(n) for n = 1..10000</a> %t A043508 Select[Range[50000], DigitCount[#, 10, 4]==4&] (* _Vincenzo Librandi_, Jul 01 2015 *) %Y A043508 Subsequence of A011534. %K A043508 nonn,base %O A043508 1,1 %A A043508 _Clark Kimberling_