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 A043580 #10 Apr 13 2021 23:11:18 %S A043580 5461,9557,10581,10837,10901,10917,10921,10923,10925,10933,10965, %T A043580 11093,11605,13653,17749,18773,19029,19093,19109,19113,19115,19117, %U A043580 19125,19157,19285,19797,20821,21077,21141,21157,21161 %N A043580 Numbers whose base-2 representation has exactly 13 runs. %t A043580 Select[Range[22000],Length[Split[IntegerDigits[#,2]]]==13&] (* _Harvey P. Dale_, May 04 2019 *) %K A043580 nonn,base %O A043580 1,1 %A A043580 _Clark Kimberling_