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A161910
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Y-toothpick sequence starting at the corner of an infinite hexagon from which protudes a half toothpick with an angle = Pi/6.
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1
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0, 1, 2, 5, 6, 9, 12, 19, 22, 25, 28, 35, 40, 47, 56, 73
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| The sequence gives the number of Y-toothpicks in the structure after n rounds. A160123 (the first differences) gives the number added at the n-th round.
See the entries A160120, A161830 and A161426 for more information about Y-toothpick sequences.
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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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FORMULA
| a(n) = (A160120(n+1)-1)/3.
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CROSSREFS
| Cf. A160120, A160121, A160123, A160406, A161830, A161831.
Sequence in context: A050487 A046962 A022486 * A151920 A160714 A094350
Adjacent sequences: A161907 A161908 A161909 * A161911 A161912 A161913
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KEYWORD
| more,nonn
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AUTHOR
| Omar E. Pol (info(AT)polprimos.com), Jun 21 2009
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