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 A043693 #10 Jun 18 2021 22:35:49 %S A043693 4,6,7,8,9,11,12,13,14,16,20,22,23,26,31,32,37,40,41,43,47,48,53,58, %T A043693 60,61,62,64,68,70,71,72,73,75,76,77,78,80,84,86,87,90,95,97,98,99, %U A043693 100,102,103,106,108,109,110,113,114,115,116,118 %N A043693 Numbers whose base-4 representation has an even number of runs. %t A043693 Select[Range[120],EvenQ[Length[Split[IntegerDigits[#,4]]]]&] (* _Harvey P. Dale_, Oct 19 2018 *) %K A043693 nonn,base %O A043693 1,1 %A A043693 _Clark Kimberling_