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 A026266 #4 Mar 30 2012 18:56:05 %S A026266 1,2,3,4,5,6,10,7,11,12,8,13,9,19,20,21,14,22,23,15,16,17,18,29,30,31, %T A026266 32,24,38,25,39,26,40,41,27,42,28,48,49,50,33,51,34,35,36,37,57,58,59, %U A026266 60,61,43,67,44,68,45,69,70,46,47,76,77,78 %N A026266 a(n) = (1/2)*s(n), where s = A026262. %K A026266 nonn %O A026266 1,2 %A A026266 _Clark Kimberling_