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 A039564 #10 Jul 01 2021 03:38:01 %S A039564 2,4,12,14,22,24,28,40,62,64,72,74,76,80,112,114,122,124,138,142,144, %T A039564 148,178,190,202,204,210,220,228,240,258,266,278,290,312,314,322,324, %U A039564 326,330,362,364,372,374,382,384,386,396,402,404,410,420,426,430,476 %N A039564 Numbers whose base-5 representation has the same number of 0's, 1's and 3's. %Y A039564 Cf. A007091. %K A039564 nonn,base,easy %O A039564 1,1 %A A039564 _Olivier Gérard_