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A161836 Number of concave-convex hexagons in the Y-toothpick structure of A160120 after n rounds. 5
0, 0, 0, 0, 3, 3, 3, 3, 9, 15 (list; graph; refs; listen; history; text; internal format)



Table of n, a(n) for n=0..9.

David Applegate, Omar E. Pol and N. J. A. Sloane, The Toothpick Sequence and Other Sequences from Cellular Automata, 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.]

N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS


Cf. A139250, A160120, A160124, A161419, A161418, A161828, A161837.

Sequence in context: A074816 A203564 A111575 * A087576 A337328 A201700

Adjacent sequences:  A161833 A161834 A161835 * A161837 A161838 A161839




Omar E. Pol, Jun 21 2009



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Last modified November 25 10:26 EST 2020. Contains 338623 sequences. (Running on oeis4.)