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%I #13 Feb 24 2021 02:48:19
%S 0,1,3,9,9,21,9,21,21,57,9,21,21,57,21,57,57,165,9,21,21,57,21,57,57,
%T 165,21,57,57,165,57,165,165,489,9,21,21,57,21,57,57,165,21,57,57,165,
%U 57,165,165,489,21,57,57,165,57,165
%N Number of toothpicks added at n-th stage to the toothpick structure of A183148.
%C Essentially the first differences of A183148.
%H 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 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 a(n) = 3*A183061(n-1), for n >=2
%e If written as a triangle begins:
%e 0,
%e 1,
%e 3,
%e 9,
%e 9,21,
%e 9,21,21,57,
%e 9,21,21,57,21,57,57,165,
%e 9,21,21,57,21,57,57,165,21,57,57,165,57,165,165,489,
%Y Cf. A139250, A139251, A147582, A147610, A160173, A161411, A183061, A183127, A183148.
%K nonn
%O 0,3
%A _Omar E. Pol_, Mar 28 2011, Apr 02 2011
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