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 A089990 #7 Jun 02 2025 00:16:59
%S A089990 1,0,2,2,0,3,1,1,0,3,1,1,1,0,4,4,4,4,4,0,5,3,3,3,3,3,0,5,3,3,3,3,3,3,
%T A089990 0,5,3,3,3,3,3,3,3,0,6,6,6,6,6,6,6,6,6,0,7,5,5,5,5,5,5,5,5,5,0,8,8,8,
%U A089990 8,8,8,8,8,8,8,8,0,8,8,8,8,8,8,8,8,8,8,8,8,0,9,7,7,7,7,7,7,7,7,7,7,7,7,0,9
%N A089990 a(n) = n step nested walk based on (A004001[n]+ (-1)^lastsum).
%C A089990 A walk based on A004001.
%t A089990 Conway[n_Integer?Positive] := Conway[n] =Conway[Conway[n-1]] + Conway[n - Conway[n-1]] Conway[1] = Conway[2] = 1 digits=20 b=Table[Conway[n], {n, 1, digits}] ChaosWalk[n_Integer?Positive] := NestList[(b[[n]]+(-1)^#)&, 0, n] ChaosWalk[1]=1 a=Flatten[Table[ChaosWalk[n], {n, 1, digits}]]
%Y A089990 Cf. A004001, A089991.
%K A089990 nonn
%O A089990 1,3
%A A089990 _Roger L. Bagula_, Jan 14 2004