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 A044874 #5 Mar 30 2012 18:56:47 %S A044874 28,29,31,35,37,38,42,43,45,49,51,52,55,56,58,62,63,66,68,71,73,74,75, %T A044874 77,2197,2198,2200,2202,2203,2206,2207,2208,2210,2213,2223,2227,2231, %U A044874 2259,2263,2267,2271,2273,2274,2275,2277,2280 %N A044874 Numbers having, in base 3, (sum of even run lengths)=(sum of odd run lengths). %K A044874 nonn,base %O A044874 1,1 %A A044874 _Clark Kimberling_