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 A100281 #17 Jan 19 2023 11:03:18 %S A100281 0,1,2,3,5,4,7,6,10,11,8,9,15,14,13,12,21,20,23,22,16,17,18,19,31,30, %T A100281 29,28,26,27,24,25,42,43,40,41,47,46,45,44,32,33,34,35,37,36,39,38,63, %U A100281 62,61,60,58,59,56,57,53,52,55,54,48,49,50,51,84,85,86,87,81,80,83,82,94 %N A100281 a(n) = A099896(A099896(n)). %C A100281 Permutation of the natural numbers with inverse A100282; %C A100281 A064707(n) = a(n) for n<64. %H A100281 Ivan Neretin, <a href="/A100281/b100281.txt">Table of n, a(n) for n = 0..8191</a> %H A100281 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %F A100281 a(n) = n XOR floor(n/4) XOR floor(n/16). - _Ivan Neretin_, Sep 06 2017 %o A100281 (Python) %o A100281 def A100281(n): return n^(m:=n>>2)^(m>>2) # _Chai Wah Wu_, Jan 19 2023 %Y A100281 Cf. A099896, A064707, A100282. %K A100281 nonn,look %O A100281 0,3 %A A100281 _Reinhard Zumkeller_, Nov 11 2004