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 A026181 #6 Sep 07 2022 13:21:06 %S A026181 3,1,2,3,3,1,2,1,2,3,1,2,3,3,1,2,3,3,1,2,1,2,3,1,2,1,2,3,1,2,3,3,1,2, %T A026181 1,2,3,1,2,3,3,1,2,3,3,1,2,1,2,3,1,2,3,3,1,2,3,3,1,2,1,2,3,1,2,1,2,3, %U A026181 1,2,3,3,1,2,1,2,3,1,2,1,2,3,1,2,3,3,1,2,1,2 %N A026181 a(n) = (1/2)*(s(n) - s(n-1)), where s = A026180. %Y A026181 Cf. A026180. %K A026181 nonn %O A026181 3,1 %A A026181 _Clark Kimberling_