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 A266533 #23 Jan 23 2016 16:22:39 %S A266533 1,3,3,9,3,9,9,21,3,9,9,21,9,21,21,45,3,9,9,21,9,21,21,45,9,21,21,45, %T A266533 21,45,45,93,3,9,9,21,9,21,21,45,9,21,21,45,21,45,45,93,9,21,21,45,21, %U A266533 45,45,93,21,45,45,93,45,93,93,189,3,9,9,21,9,21,21,45,9,21,21,45,21,45,45,93 %N A266533 First differences of A266532. %C A266533 Number of Y-toothpicks added at n-th stage in the structure of A266532. %C A266533 A simplified version of A160121. %H A266533 David Applegate, <a href="/A139250/a139250.anim.html">The movie version</a> %H A266533 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 A266533 <a href="/index/Ce#cell">Index entries for sequences related to cellular automata</a> %H A266533 <a href="/index/To#toothpick">Index entries for sequences related to toothpick sequences</a> %F A266533 a(1) = 1. It appears that a(n) = 3*A038573(n-1), n >= 2. %e A266533 Written as an irregular triangle in which the row lengths are the terms of A011782 the sequence begins: %e A266533 1; %e A266533 3; %e A266533 3, 9; %e A266533 3, 9, 9, 21; %e A266533 3, 9, 9, 21, 9, 21, 21, 45; %e A266533 3, 9, 9, 21, 9, 21, 21, 45, 9, 21, 21, 45, 21, 45, 45, 93; %e A266533 ... %e A266533 Observation: at least the first 11 terms of the right border coincide with A068156. %Y A266533 Cf. A000120, A011782, A038573, A068156. A139251, A147582, A160121, A151710, A160721, A266532, A267701. %K A266533 nonn,tabf %O A266533 1,2 %A A266533 _David Applegate_ and _Omar E. Pol_, Jan 18 2016