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 A161833 #6 Feb 24 2021 02:48:18 %S A161833 1,1,2,1,2,2,4,2,2,2,4,3,4,5,9,5,2 %N A161833 First differences of A161832. %C A161833 Number of Y-toothpicks added to the sieve at the n-th round. %H A161833 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 A161833 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> %F A161833 a(n) = A161831(n+1)/2. %Y A161833 Cf. A139251, A160121, A160407, A161830, A161831, A161832. %K A161833 more,nonn %O A161833 1,3 %A A161833 _Omar E. Pol_, Jun 20 2009