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 A026249 #4 Mar 30 2012 18:56:05 %S A026249 1,2,1,3,4,2,5,6,7,3,8,9,4,10,11,12,5,13,14,6,15,16,7,17,18,19,8,20, %T A026249 21,9,22,23,24,10,25,26,11,27,28,12,29,30,31,13,32,33,14,34,35,36,15, %U A026249 37,38,16,39,40,41,17,42,43,18,44,45,19,46,47,48 %N A026249 a(n) = j if n = [ j*sqrt(2) ], else a(n) = k if n = [ k*(2 + sqrt(2)) ]. %K A026249 nonn %O A026249 1,2 %A A026249 _Clark Kimberling_