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 A160418 #18 Aug 15 2025 00:58:37 %S A160418 1,1,1,1,2,2,1,1,2,2,2,3,5,4,1,1,2,2,2,3,5,4,2,3,5,5,6,10,13,8,1,1,2, %T A160418 2,2,3,5,4,2,3,5,5,6,10,13,8,2,3,5,5,6,10,13,9,6,10,14,15,21,32,33,16, %U A160418 1,1,2,2,2,3,5,4,2,3,5,5,6,10,13,8,2,3,5,5 %N A160418 a(n) = A160407(n+2)/2. %C A160418 Row lengths are the terms of A000079 multiplied by 2. Right border gives A000079. - _Omar E. Pol_, Mar 19 2020 %H A160418 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 A160418 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> %e A160418 From _Omar E. Pol_, Mar 19 2020: (Start) %e A160418 Triangle begins: %e A160418 1,1; %e A160418 1,1,2,2; %e A160418 1,1,2,2,2,3,5,4; %e A160418 1,1,2,2,2,3,5,4,2,3,5,5,6,10,13,8; %e A160418 1,1,2,2,2,3,5,4,2,3,5,5,6,10,13,8,2,3,5,5,6,10,13,9,6,10,14,15,21,32,33,16; %e A160418 ... (End) %Y A160418 Cf. A139250, A139251, A160160, A160161, A160406, A160407, A160408, A160409. %K A160418 nonn,tabf %O A160418 1,5 %A A160418 _Omar E. Pol_, May 23 2009 %E A160418 More terms from _Jinyuan Wang_, Mar 14 2020