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 A342682 #20 Oct 14 2021 18:08:19 %S A342682 1,0,1,-1,1,1,0,-1,0,-1,2,0,1,1,-1,0,-1,1,-1,-2,1,0,2,-1,1,-1,2,1,0,0, %T A342682 -1,1,-1,-1,0,1,0,2,-3,-1,-1,0,1,-2,2,1,1,-1,0,1,0,-2,1,-1,3,0,1,0,0, %U A342682 1,-1,-1,0,1,0,1,-2,0,-1,-1,1,0,1,-2,2,3,-1,1,-4 %N A342682 a(1) = 1; for n > 0: a(2*n) = -a(n+1), a(2*n+1) = a(n) + a(n+1). %H A342682 Michael De Vlieger, <a href="/A342682/b342682.txt">Table of n, a(n) for n = 1..10000</a> %H A342682 George Beck and Karl Dilcher, <a href="https://arxiv.org/abs/2106.10400">A Matrix Related to Stern Polynomials and the Prouhet-Thue-Morse Sequence</a>, arXiv:2106.10400 [math.CO], 2021. %e A342682 a(2) = -a(2), so a(2) = 0; a(11) = a(5) + a(6) = 1 + 1 = 2. %t A342682 a@1 = 1; %t A342682 a@2 = 0; %t A342682 a@n_ := -a[n/2 + 1] /; EvenQ@n; %t A342682 a@n_ := a[1/2 (n - 1)] + a[1/2 (n - 1) + 1] /; OddQ@n; %t A342682 a /@ Range[128] %Y A342682 Cf. A002487, A213369, A082498. %K A342682 sign %O A342682 1,11 %A A342682 _George Beck_, May 18 2021