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 A269868 #9 Mar 07 2016 07:40:54
%S A269868 1,3,4,2,6,8,5,7,12,14,16,17,18,20,19,9,15,10,24,25,28,26,29,11,13,32,
%T A269868 34,33,21,37,35,22,30,23,27,49,50,48,53,31,56,58,64,65,66,68,67,69,70,
%U A269868 72,71,73,74,77,75,78,80,82,85,76,79,88,90,36,38,51,59,39,54,63,57,40
%N A269868 Lexicographically earliest sequence of distinct positive integers such that all values of (a(n) XOR n) are distinct.
%H A269868 Ivan Neretin, <a href="/A269868/b269868.txt">Table of n, a(n) for n = 1..10000</a>
%t A269868 a = used = {}; Do[k = 1; While[MemberQ[a, k] || MemberQ[used, x = BitXor[k, n]], k++]; AppendTo[a, k]; AppendTo[used, x], {n, 72}]; a
%Y A269868 Cf. A235262
%K A269868 nonn
%O A269868 1,2
%A A269868 _Ivan Neretin_, Mar 06 2016