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 A300839 #5 Apr 15 2018 15:05:31
%S A300839 0,3,1,2,15,12,14,13,7,4,6,5,8,11,9,10,63,60,62,61,48,51,49,50,56,59,
%T A300839 57,58,55,52,54,53,31,28,30,29,16,19,17,18,24,27,25,26,23,20,22,21,32,
%U A300839 35,33,34,47,44,46,45,39,36,38,37,40,43,41,42,255,252,254,253,240,243,241,242,248,251,249,250,247,244,246,245,192
%N A300839 Permutation of nonnegative integers: a(n) = A006068(A057300(n)).
%H A300839 Antti Karttunen, <a href="/A300839/b300839.txt">Table of n, a(n) for n = 0..16383</a>
%H A300839 <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>
%H A300839 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>
%F A300839 a(n) = A006068(A057300(n)).
%o A300839 (PARI)
%o A300839 A006068(n)= { my(s=1, ns); while(1, ns = n >> s; if(0==ns, break()); n = bitxor(n, ns); s <<= 1; ); return (n); } \\ From A006068
%o A300839 A057300(n) = { my(t=1, s=0); while(n>0, if(1==(n%4),n++,if(2==(n%4),n--)); s += (n%4)*t; n >>= 2; t <<= 2); (s); };
%o A300839 A300839(n) = A006068(A057300(n));
%Y A300839 Cf. A300838 (inverse permutation).
%K A300839 nonn,base
%O A300839 0,2
%A A300839 _Antti Karttunen_, Apr 15 2018