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 A161426 #8 Feb 24 2021 02:48:18 %S A161426 0,1,4,7,14,19,26,35,52,63,70 %N A161426 Y-toothpick sequence starting at the outside corner of an infinite triangle-shaped polygon as the sieve of A160120 after 2^k rounds. %C A161426 The sequence gives the number of Y-toothpicks after n rounds. A161427 (the first differences) gives the number added at the n-th round. %C A161426 See the entries A160120, A139250 and A153006 for more information. %H A161426 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 A161426 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> %H A161426 David Applegate, <a href="/A139250/a139250.anim.html">The movie version</a> %Y A161426 Cf. A000079, A139250, A153006, A160120, A161427, A161830. %K A161426 more,nonn %O A161426 0,3 %A A161426 _Omar E. Pol_ and _David Applegate_, Jun 20 2009