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