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 A161838 #6 Feb 24 2021 02:48:18 %S A161838 0,0,0,0,1,1,1,1,3,5 %N A161838 a(n) = A161836(n)/3. %H A161838 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 A161838 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> %Y A161838 Cf. A160120, A161422, A161834, A161836, A161837. %K A161838 more,nonn %O A161838 0,9 %A A161838 _Omar E. Pol_, Jun 21 2009