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 A174218 #4 Jul 22 2025 07:52:35
%S A174218 1,0,-2,1,5,10,16,9,17,26,16,5,-7,6,-8,7,23,6,-12,7,-13,8,30,7,31,6,
%T A174218 32,5,33,4,34,3,35,2,-32,-67,-31,-68,-30,-69,-29,12,54,11,55,100,54,
%U A174218 101,149,100,150,99,47,-6,48,-7,-63,-120,-62,-121,-61,-122,-184,-247,-183
%N A174218 An absolute difference sequence based on A087655: a(n)=If[Mod[A087655(n), 3] == 1, a(n - 1) - (-1)^n*n, a(n - 1) + (-1)^n*n].
%C A174218 Abs[a(n)-a(n-1)]=n
%t A174218 (*A087655[n]*)
%t A174218 Rauzy[n_Integer?Positive] := Rauzy[n] = Rauzy[ Abs[n - Rauzy[n - 1]]] + Rauzy[Abs[n - Rauzy[n - 2]]] + Rauzy[Abs[n - Rauzy[n - 3]]];
%t A174218 Rauzy[0] = Rauzy[1] = Rauzy[2] = Rauzy[3] = 1;
%t A174218 a[0] := 1; a[1] := 0;
%t A174218 a[n_] := a[n] = If[ Mod[Rauzy[n], 3] == 1, a[n - 1] - (-1)^n*n, a[n - 1] + (-1)^n*n];
%t A174218 Table[a[n], {n, 0, 200}]
%K A174218 sign,uned
%O A174218 0,3
%A A174218 _Roger L. Bagula_, Mar 12 2010