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 A206960 #25 Dec 06 2018 16:34:52
%S A206960 0,1,4,9,31,66,190,385,1022,2055,5112,10242,24572,49153,114686,229377,
%T A206960 524287,1048590,2359281,4718599,10485753,20971521,46137342,92274689,
%U A206960 201326590,402653191,872415224,1744830466,3758096380,7516192769,16106127358,32212254721
%N A206960 a(0)=0, a(1)=1, for n>1, a(n) = n<*>n, where k<*>m = k<+>k<+>...<+>k is the m-1-fold iteration of the operation <+> defined in A206853.
%C A206960 A Hamming's analog of n^2.
%F A206960 A010060(a(n)) = A010060(n). - _Vladimir Shevelev_ and _Alois P. Heinz_, Feb 17 2012
%t A206960 f[n_,k_]:=Module[{i=n+1},While[Count[IntegerDigits[BitXor[n,i],2],1]!=k,i++]; i]; Join[{0,1},Table[Nest[f[#,k]&,k,k-1],{k,2,18}]] (* _Jayanta Basu_, May 26 2013 *)
%Y A206960 Cf. A205509, A205510, A205511, A205302, A205649, A205533, A122565, A206852, A206853.
%K A206960 nonn,base
%O A206960 0,3
%A A206960 _Vladimir Shevelev_ and Konstantin Shukhmin (shukhmin(AT)callsouth.net.nz), Feb 14 2012
%E A206960 a(11)-a(31) from _Alois P. Heinz_, Feb 16 2012