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 A175099 #7 Feb 24 2021 02:48:19 %S A175099 0,0,0,0,1,0,0,2,3,0,0,2,2,0,0,4,7,0,0,2,2,0,0,4,6,0,0,4,4,0,0,8,15,0, %T A175099 0,2,2,0,0,4,6,0,0,4,4,0,0,8,14,0,0,4,4,0,0,8,12,0,0,8,8,0,0,16,31,0, %U A175099 0,2,2,0,0,4,6,0,0,4,4,0,0,8,14,0,0,4,4,0,0,8,12,0,0,8,8,0,0,16,30,0,0,4,4,0 %N A175099 Number of closed rectangles added at the n-th stage of the leftist toothpicks A151566. %H A175099 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 A175099 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 A175099 For a recurrence see A160018. - _N. J. A. Sloane_, Feb 07 2010 %Y A175099 Cf. A160125, A175098 %K A175099 nonn %O A175099 0,8 %A A175099 _R. J. Mathar_, Feb 04 2010