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 A043709 #8 Jun 18 2021 23:04:37 %S A043709 1,2,3,4,5,7,14,21,28,35,37,38,39,40,41,43,48,49,51,52,53,54,55,56,58, %T A043709 59,60,61,62,63,65,66,67,68,69,70,73,74,75,76,77,78,80,81,82,83,86,90, %U A043709 91,92,94,95,96,97,98,99,101,102,103,104 %N A043709 Numbers whose base-6 representation has an odd number of runs. %K A043709 nonn,base %O A043709 1,2 %A A043709 _Clark Kimberling_