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A161426 Y-toothpick sequence starting at the outside corner of an infinite triangle-shaped polygon as the sieve of A160120 after 2^k rounds. 2
0, 1, 4, 7, 14, 19, 26, 35, 52, 63, 70 (list; graph; refs; listen; history; text; internal format)



The sequence gives the number of Y-toothpicks after n rounds. A161427 (the first differences) gives the number added at the n-th round.

See the entries A160120, A139250 and A153006 for more information.


Table of n, a(n) for n=0..10.

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

David Applegate, The movie version


Cf. A000079, A139250, A153006, A160120, A161427, A161830.

Sequence in context: A049766 A244905 A310920 * A115759 A157615 A188319

Adjacent sequences:  A161423 A161424 A161425 * A161427 A161428 A161429




Omar E. Pol and David Applegate, Jun 20 2009



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Last modified January 16 19:49 EST 2019. Contains 319206 sequences. (Running on oeis4.)