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 A099896 #15 Sep 06 2017 21:21:37
%S A099896 1,3,2,7,6,4,5,14,15,13,12,9,8,10,11,28,29,31,30,27,26,24,25,18,19,17,
%T A099896 16,21,20,22,23,56,57,59,58,63,62,60,61,54,55,53,52,49,48,50,51,36,37,
%U A099896 39,38,35,34,32,33,42,43,41,40,45,44,46,47,112,113,115,114,119,118,116
%N A099896 A permutation of the natural numbers where a(n) = n XOR [n/2] XOR [n/4].
%C A099896 Related to Gray code numbers (A003188) since A003188(n) = n XOR [n/2].
%C A099896 Inverse: A100280; A100281(n) = a(a(n)). - _Reinhard Zumkeller_, Nov 11 2004
%H A099896 Ivan Neretin, <a href="/A099896/b099896.txt">Table of n, a(n) for n = 1..8191</a>
%H A099896 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>
%F A099896 XOR BINOMIAL transform begins: B={1, 2, 3, 7, 7, 0, 0, 14, 14, 0, 0, ...} and continues with B(2^k)=B(2^k+1)=7*2^(k-2) (for k>=2) and zeros elsewhere.
%t A099896 Array[BitXor[BitXor[#,Floor[#/2]],Floor[#/4]]&,70] (* _Harvey P. Dale_, Aug 10 2012 *)
%o A099896 (PARI) a(n)=bitxor(bitxor(n,n\2),n\4)
%Y A099896 Cf. A003188, A099884.
%K A099896 nonn,look
%O A099896 1,2
%A A099896 _Paul D. Hanna_, Nov 09 2004