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A161328
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E-Toothpick sequence (see Comments lines for definition).
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12
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0, 1, 4, 9, 16, 29, 40, 57, 72, 93, 116, 141, 168, 201, 228, 253, 268, 293, 328, 369, 424, 477, 536, 597, 656, 721, 784, 841, 888, 925, 972, 1037, 1108, 1205, 1300, 1405, 1500, 1589, 1672, 1753, 1840, 1933, 2012, 2085, 2164, 2253, 2360, 2473, 2592, 2705, 2820
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| An E-Toothpick is formed by three half toothpicks, as a trident.
On the infinite triangular grid, we start at round 0 with no E-Toothpicks.
At round 1 we place an E-Toothpick anywhere in the plane.
At round 2 we place three other E-Toothpicks.
At round 3 we place five other E-Toothpicks.
And so on...
A special rule is ... (Needs definition)
The sequence gives the number of E-Toothpicks after n rounds. A161329 (the first differences) gives the number added at the n-th round.
See the entry A139250 for more information about the toothpick process and the toothpick propagation.
Note that, on the infinite triangular grid, a E-Toothpick can be represented as a polyedge with three components. In this case, at n-th round, the structure is a polyedge with 3*a(n) components.
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LINKS
| David Applegate, Omar E. Pol and N. J. A. Sloane, The Toothpick Sequence and Other Sequences from Cellular Automata
N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS
Index entries for sequences related to toothpick sequences [From Omar E. Pol (info(AT)polprimos.com), Dec 06 2009]
Index entries for sequences related to cellular automata [From Omar E. Pol (info(AT)polprimos.com), Dec 06 2009]
O. E. Pol, Illustration of initial terms of A160120, A161206, A161328, A161330 (Triangular grid and toothpicks) [From Omar E. Pol (info(AT)polprimos.com), Dec 06 2009]
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CROSSREFS
| Cf. A139250, A139251, A160120, A160172, A161329, A161330.
Cf. A161206. [From Omar E. Pol (info(AT)polprimos.com), Dec 06 2009]
Sequence in context: A113495 A110997 A001640 * A073141 A093175 A138992
Adjacent sequences: A161325 A161326 A161327 * A161329 A161330 A161331
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KEYWORD
| nonn
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AUTHOR
| Omar E. Pol (info(AT)polprimos.com), Jun 07 2009
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EXTENSIONS
| a(8) corrected, more terms appended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 21 2010
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