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 A026227 #4 Mar 30 2012 18:56:05 %S A026227 1,3,6,7,9,12,15,16,18,19,21,24,25,27,30,33,34,36,39,42,43,45,46,48, %T A026227 51,52,54,55,57,60,61,63,66,69,70,72,73,75,78,79,81,84,87,88,90,93,96, %U A026227 97,99,100,102,105,106,108,111,114,115,117,120 %N A026227 a(n) = (1/3)*(s(n) + 2), where s = A026226. %K A026227 nonn %O A026227 1,2 %A A026227 _Clark Kimberling_