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A161830
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Y-toothpick triangle (see Comments lines for definition).
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8
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0, 1, 3, 5, 9, 11, 15, 19, 27, 31, 35, 39, 47, 53, 61, 71, 89, 99, 103
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| Y-toothpick sequence starting at the corner of an infinite hexagon in which its vertex touch an endpoint of the initial Y-toothpick and the two other endpoints are equidistant from the nearest sides of the hexagon.
The sequence gives the number of Y-toothpicks in the structure after n rounds. A161831 (the first differences) gives the number added at the n-th round.
See the Y-toothpick sequence A160120 for more information about the recursive, fractal-like structure.
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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
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CROSSREFS
| Cf. A139250, A160120, A160121, A160406, A160407, A161831, A161832, A161833.
Sequence in context: A075991 A002731 A006046 * A151922 A104635 A199407
Adjacent sequences: A161827 A161828 A161829 * A161831 A161832 A161833
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KEYWORD
| more,nonn
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AUTHOR
| Omar E. Pol (info(AT)polprimos.com), Jun 20 2009
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