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 A160018 #6 Feb 24 2021 02:48:18 %S A160018 0,0,0,1,1,0,0,2,3,0,0,2,2,0,0,4,7,0,0,2,2,0,0,4,6,0,0,4,4,0,0,8,15,0, %T A160018 0,2,2,0,0,4,6,0,0,4,4,0,0,8,14,0,0,4,4,0,0,8,12,0,0,8,8,0,0,16,31,0, %U A160018 0,2,2,0,0,4,6,0,0,4,4,0,0,8,14,0,0,4,4,0,0,8,12,0,0,8,8,0,0,16,30,0,0,4,4,0 %N A160018 A175099 with a(3) changed from 0 to 1. %H A160018 David Applegate, Omar E. Pol and N. J. A. Sloane, <a href="/A000695/a000695_1.pdf">The Toothpick Sequence and Other Sequences from Cellular Automata</a>, Congressus Numerantium, Vol. 206 (2010), 157-191. [There is a typo in Theorem 6: (13) should read u(n) = 4.3^(wt(n-1)-1) for n >= 2.] %H A160018 N. J. A. Sloane, <a href="/wiki/Catalog_of_Toothpick_and_CA_Sequences_in_OEIS">Catalog of Toothpick and Cellular Automata Sequences in the OEIS</a> %F A160018 a(n) = a(1) = 0; for k >= 1, a(2^k) = 2^(k-1)-1, a(2^k+i) = 2*a(i) for 1 <= i < 2^k. %Y A160018 Cf. A160125, A175098, A175099. %K A160018 nonn %O A160018 0,8 %A A160018 _N. J. A. Sloane_, Feb 07 2010