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A172308
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L-toothpick sequence in the first quadrant.
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7
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0, 1, 3, 5, 7, 11, 15, 17, 21, 27, 33, 41, 47, 59, 69, 75, 79, 85, 95, 107, 117, 131, 145, 161, 177, 195, 209, 225, 237, 257, 279, 287, 295, 311, 329, 345, 355, 371, 391, 415, 441, 477, 501, 533, 563, 603, 631, 655
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listen;
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internal format)
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OFFSET
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0,3
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COMMENTS
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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.
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LINKS
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CROSSREFS
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Cf. A139250, A153000, A160120, A160170, A160172, A161206, A161328, A172304, A172305, A172306, A172307, A172309, A172310, A172311, A172312, A172313.
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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