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 A175947 #4 Mar 31 2012 20:25:48
%S A175947 1,0,3,-2,1,2,7,-6,-1,0,3,0,5,6,15,-14,-5,-4,1,-2,3,2,7,-4,3,4,11,4,
%T A175947 13,14,31,-30,-13,-12,-3,-10,-1,-2,5,-6,1,0,9,0,7,6,15,-12,-1,0,9,2,
%U A175947 11,10,23,0,11,12,27,12,29,30,63,-62,-29,-28,-11,-26,-9,-10,1,-22,-7,-8,5,-8
%N A175947 A175945(n)-A175946(n).
%t A175947 takelist[l_, t_] := Module[{lent, term},Set[lent, Length[t]]; Table[l[[t[[y]]]], {y, 1, lent}]]
%t A175947 frombinrep[x_] := FromDigits[Flatten[Table[Table[If[OddQ[n], 1, 0], {d, 1, x[[n]]}], {n, 1, Length[x]}]], 2]
%t A175947 binrep[x_] := repcount[IntegerDigits[x, 2]]
%t A175947 onebinrep[x_]:=Module[{b},b=binrep[x];takelist[b,Range[1,Length[b],2]]]
%t A175947 zerobinrep[x_]:=Module[{b},b=binrep[x];takelist[b,Range[2,Length[b],2]]]
%t A175947 Table[frombinrep[onebinrep[n]], {n,START,END}]-Table[frombinrep[zerobinrep[n]], {n,START,END}]
%K A175947 base,sign
%O A175947 1,3
%A A175947 _Dylan Hamilton_, Oct 28 2010