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A172308 L-toothpick sequence in the first quadrant. 6
0, 1, 3, 5, 7, 11, 15, 17, 21, 27, 33, 41, 47, 59, 69, 75, 79 (list; graph; refs; listen; history; text; internal format)



The same as A172310 and A172304, but starting from half L-toothpick in the first quadrant.

Note that if n is odd then we add the small L-toothpicks to the structure, otherwise we add the large L-toothpicks to the structure.

We start at stage 0 with half L-toothpick: A segment from (0,0) to (1,1).

At stage 1 we place a small L-toothpick at the exposed toothpick end.

At stage 2 we place two large L-toothpicks.

At stage 3 we place two small L-toothpicks.

At stage 4 we place two large L-toothpicks.

And so on...

The sequence gives the number of L-toothpicks after n stages. A172309 (the first differences) gives the number of L-toothpicks added at the n-th stage.


Table of n, a(n) for n=0..16.

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, A153000, A160120, A160170, A160172, A161206, A161328, A172304, A172305, A172306, A172307, A172309, A172310, A172311, A172312, A172313.

Sequence in context: A139252 A076245 A318953 * A190812 A238738 A059748

Adjacent sequences:  A172305 A172306 A172307 * A172309 A172310 A172311




Omar E. Pol, Feb 06 2010



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Last modified April 23 09:35 EDT 2019. Contains 322385 sequences. (Running on oeis4.)