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 A177240 #6 Feb 24 2021 02:48:19 %S A177240 0,1,5,9,25,29,45 %N A177240 Number of K-toothpicks after n stages of 3-D K-toothpick structure defined in Comments. %C A177240 We are in 3-D. Here the polytoothpick is a K-toothpick. The K-toothpick has 4 components or line segments, a central point and 4 endpoints, as a tetrapod but without volume. The K-toothpick endpoints coincide with the vertices of a regular tetrahedron. %C A177240 It appears that this is a three-dimensional version of A160120, but with K-toothpicks, not with Y-toothpick. %C A177240 The first differences are in the entry A177241. %C A177240 For the toothpick mechanism see A139250 and A160120. %C A177240 Question: Is this the same as A116520? (To answer the question we need a program because the structure is hard to visualize). %H A177240 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 A177240 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 A177240 Cf. A102376, A116520, A139250, A160120, A177241. %K A177240 more,nonn %O A177240 0,3 %A A177240 _Omar E. Pol_, May 05 2010 %E A177240 Edited by _Omar E. Pol_, May 07 2010