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 A356399 #9 Aug 07 2022 15:37:05
%S A356399 1,2,1,-1,5,1,2,1,-1,-3,1,-1,13,1,2,1,-1,5,1,2,1,-1,-3,1,-1,-8,1,2,1,
%T A356399 -1,-3,1,-1,34,1,2,1,-1,5,1,2,1,-1,-3,1,-1,13,1,2,1,-1,5,1,2,1,-1,-3,
%U A356399 1,-1,-8,1,2,1,-1,-3,1,-1,-21,1,2,1,-1,5,1,2,1,-1
%N A356399 a(n) is the smallest term (in absolute value) in the negaFibonacci representation of n.
%C A356399 See A139764 and A356400 for similar sequences.
%C A356399 For n > 1, the greatest term in the negaFibonacci representation of n is A280511(n-1).
%H A356399 Rémy Sigrist, <a href="/A356399/b356399.txt">Table of n, a(n) for n = 1..10946</a>
%H A356399 Wikipedia, <a href="https://en.wikipedia.org/wiki/NegaFibonacci_coding">NegaFibonacci coding</a>
%H A356399 <a href="/index/Z#Zeckendorf">Index entries for sequences related to Zeckendorf expansion of n</a>
%F A356399 a(n) = n iff n belongs to A001519.
%e A356399 For n = 11:
%e A356399 - using F(-k) = A039834(k):
%e A356399 - 11 = F(-1) + F(-4) + F(-7),
%e A356399 - so a(11) = F(-1) = 1.
%o A356399 (PARI) a(n) = { my (v=0, neg=0, pos=0, f); for (e=0, oo, f=fibonacci(-1-e); if (f<0, neg+=f, pos+=f); if (neg <=n && n <= pos, while (n, if (f<0, neg-=f, pos-=f); if (neg > n || n > pos, v=f; n-=f;); f=fibonacci(-1-e--);); return (v););); }
%Y A356399 Cf. A001519, A039834, A139764, A280511, A356400.
%K A356399 sign,base
%O A356399 1,2
%A A356399 _Rémy Sigrist_, Aug 06 2022