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 A039010 #13 Jun 20 2021 19:19:57 %S A039010 0,3,4,7,11,15,18,19,20,23,24,27,35,38,39,42,47,51,55,58,59,66,71,75, %T A039010 78,79,82,86,90,93,94,95,98,99,100,103,104,107,111,115,118,119,120, %U A039010 123,124,127,135,138,139,142,147,162,175,178,179,182,186,190,193,194 %N A039010 Numbers whose base-5 representation has the same number of 1's and 2's. %H A039010 Daniel Starodubtsev, <a href="/A039010/b039010.txt">Table of n, a(n) for n = 1..10000</a> %Y A039010 Cf. A007091. %K A039010 nonn,base,easy %O A039010 1,2 %A A039010 _Olivier Gérard_