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%I A161828 #6 Feb 24 2021 02:48:18
%S A161828 0,0,3,3,9,9,15,21,33,39
%N A161828 Number of rhombuses in the Y-toothpick structure of A160120 after n rounds.
%H A161828 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 A161828 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>
%Y A161828 Cf. A139250, A160120, A160124, A161419, A161418, A161836.
%K A161828 more,nonn
%O A161828 0,3
%A A161828 _Omar E. Pol_, Jun 21 2009

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