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 A031476 #7 Jul 04 2021 15:53:11 %S A031476 124,249,374,499,549,574,599,609,614,619,621,622,623,874,999,1124, %T A031476 1174,1199,1224,1234,1239,1244,1246,1247,1248,1499,1624,1749,1799, %U A031476 1824,1849,1859,1864,1869,1871,1872,1873,2124,2249 %N A031476 Numbers whose base-5 representation has 3 fewer 0's than 4's. %Y A031476 Cf. A007091. %K A031476 nonn,base %O A031476 1,1 %A A031476 _Clark Kimberling_