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 A071906 #11 Apr 21 2017 02:57:25
%S A071906 1,0,0,0,1,1,0,1,1,0,1,0,1,0,0,0,1,0,1,1,1,0,1,1,1,1,0,1,1,1,1,1,0,0,
%T A071906 1,1,0,0,1,1,1,0,0,0,0,0,0,0,1,1,0,0,1,1,0,0,1,0,0,1,0,0,1,1,0,0,1,0,
%U A071906 1,1,0,0,1,0,0,1,0,0,0,0,0,1,0,0,0,0,0,1,1,1,0,0,1,1,1,0,1,1,0,1,1,1,0,0,1
%N A071906 Sum of digits of 2^n (mod 2).
%H A071906 G. C. Greubel, <a href="/A071906/b071906.txt">Table of n, a(n) for n = 0..10000</a>
%t A071906 f[n_] := Mod[Plus @@ IntegerDigits[2^n], 2]; Table[ f@n, {n, 0, 104}] (* _Robert G. Wilson v_, May 04 2009 *)
%o A071906 (PARI) a(n) = sumdigits(2^n) % 2; \\ _Michel Marcus_, Apr 20 2017
%Y A071906 Cf. A001370.
%K A071906 base,nonn
%O A071906 0,1
%A A071906 _Santi Spadaro_, Jun 13 2002