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 A173465 #6 Feb 24 2021 02:48:19 %S A173465 1,1,3,1,3,3,7,1,3,3,7,5,7,9,17,1,3,3,7,5,7,9,17,7,7,9,17,17,19,23,39, %T A173465 1 %N A173465 a(n) = A151710(n+1)/3. %C A173465 First 23 terms the same as A151837. %H A173465 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 A173465 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 A173465 If written as a triangle, begins: %e A173465 1; %e A173465 1,3; %e A173465 1,3,3,7; %e A173465 1,3,3,7,5,7,9,17; %e A173465 1,3,3,7,5,7,9,17,7,7,9,17,17,19,23,39; %Y A173465 Cf. A139251, A151837, A160120, A160121, A160123. %K A173465 more,nonn,tabf %O A173465 1,3 %A A173465 _Omar E. Pol_, May 29 2010