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 A161427 #8 Feb 24 2021 02:48:18 %S A161427 1,3,3,7,5,7,9,17,11,7 %N A161427 First differences of A161426. %C A161427 Number of Y-toothpicks added to the sieve at the n-th round. %H A161427 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 A161427 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 A161427 David Applegate, <a href="/A139250/a139250.anim.html">The movie version</a> %Y A161427 Cf. A139251, A152980, A160121, A161426, A161831. %K A161427 more,nonn %O A161427 1,2 %A A161427 _Omar E. Pol_ and _David Applegate_, Jun 20 2009