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 A043706 #10 Jun 18 2021 19:58:46 %S A043706 1,2,4,8,10,11,13,15,16,19,20,21,23,26,28,29,31,35,37,38,40,42,43,45, %T A043706 49,51,52,55,56,58,62,63,66,68,71,73,74,75,77,80,82,83,85,89,91,92,94, %U A043706 96,97,100,101,102,104,107,109,110,112,116,118 %N A043706 Numbers whose base-3 representation has an odd number of runs. %t A043706 Select[Range[200],OddQ[Length[Split[IntegerDigits[#,3]]]]&] (* _Harvey P. Dale_, Mar 05 2020 *) %K A043706 nonn,base %O A043706 1,2 %A A043706 _Clark Kimberling_