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 A043713 #8 Jun 18 2021 23:07:28 %S A043713 1,2,3,4,5,6,7,8,9,11,22,33,44,55,66,77,88,99,101,102,103,104,105,106, %T A043713 107,108,109,111,120,121,123,124,125,126,127,128,129,130,131,132,134, %U A043713 135,136,137,138,139,140,141,142,143,145,146 %N A043713 Numbers whose base-10 representation has an odd number of runs. %K A043713 nonn,base %O A043713 1,2 %A A043713 _Clark Kimberling_