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 A161413 #6 Feb 24 2021 02:48:18 %S A161413 1,1,1,2,4,3,3,4,6,4,5,5,10,9,5 %N A161413 First differences of A161412. %C A161413 Number of V-toothpicks added to the structure at the n-th round. %H A161413 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 A161413 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 A161413 Cf. A139251, A160121, A160407, A161207, A161329, A161412. %K A161413 more,nonn %O A161413 1,4 %A A161413 _Omar E. Pol_, Jun 10 2009