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 A309022 #5 Jul 06 2019 20:58:54
%S A309022 0,1,-1,-2,1,-2,2,4,-1,-1,2,3,-2,4,-4,-7,1,-4,1,4,-2,2,-3,-7,2,3,-4,
%T A309022 -6,4,-7,7,12,-1,2,4,4,-1,7,-4,-7,2,0,-2,-3,3,-6,7,12,-2,8,-3,-9,4,-5,
%U A309022 6,14,-4,-5,7,10,-7,12,-12,-20,1,-9,-2,3,-4,-2,-4,-9,1,4,-7,-10,4,-10,7,13,-2,5,0,-4,2,-1,3,8,-3,-6,6
%N A309022 Expansion of x * Product_{k>=0} (1 - x^(2^k) - x^(2^(k+1)) - x^(2^(k+2))).
%F A309022 a(0) = 0, a(1) = 1; a(2*n) = -a(n), a(2*n+1) = a(n+1) - a(n) - a(n-1).
%t A309022 nmax = 90; CoefficientList[Series[x Product[(1 - x^(2^k) - x^(2^(k + 1)) - x^(2^(k + 2))), {k, 0, Floor[Log[2, nmax]] + 1}], {x, 0, nmax}], x]
%t A309022 a[0] = 0; a[1] = 1; a[n_] := If[EvenQ[n], -a[n/2], a[(n + 1)/2] - a[(n - 1)/2] - a[(n - 3)/2]]; Table[a[n], {n, 0, 90}]
%Y A309022 Cf. A002487, A177219, A309019, A309020, A309021.
%K A309022 sign
%O A309022 0,4
%A A309022 _Ilya Gutkovskiy_, Jul 06 2019