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A222180 Total number of ON states after n generations of cellular automaton based on pentagons. Also P-toothpick sequence (see Comments lines for definition). 5
0, 1, 6, 16, 26, 36, 56, 86, 106, 116, 136, 176, 216, 246, 296, 366, 406, 416, 436, 476, 536, 616 (list; graph; refs; listen; history; text; internal format)



Analog of A161644, A147562 and A151723, but here we are working without a lattice. Each regular pentagon has five virtual neighbors. Overlapping are prohibited. The sequence gives the number of pentagons in the structure after n-th stage. A222181 (the first differences) gives the number of pentagons added at n-th stage.

Also this is a P-toothpick sequence since every pentagon can be replaced by a P-toothpick which is formed by five toothpicks as a five-pointed star. Note that each toothpick can be represented as an apothem or as a radius of a pentagon. In both types of structures the number of toothpicks after n-th stage is equal to 5*a(n).


Table of n, a(n) for n=0..21.

Omar E. Pol, Illustration of structure after 5 stages, (Contains 36 pentagons).

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

Index entries for sequences related to toothpick sequences


a(n) = 6 + 10*A222172(n-2), n >= 2. - Omar E. Pol, Nov 24 2013


Cf. A139250, A147562, A151723, A152968, A161330, A161644, A182632, A182840, A222172, A222176, A222181.

Sequence in context: A017341 A232491 A191157 * A212905 A191117 A265389

Adjacent sequences:  A222177 A222178 A222179 * A222181 A222182 A222183




Omar E. Pol, Mar 15 2013


Name improved by Omar E. Pol, Nov 24 2013



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Last modified August 3 10:28 EDT 2020. Contains 336198 sequences. (Running on oeis4.)