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A160426
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Toothpick sequence starting from an asymmetric cross, with four edges of length 1, 2, 3 and 4, formed by five toothpicks of length 2.
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10
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0, 5, 9, 17, 30, 42, 52, 69, 90, 102, 112, 129, 150, 170, 196, 237, 274, 286, 296, 313, 334, 354, 380, 421, 458, 478, 504, 545, 590, 642, 724, 829, 898, 910, 920, 937, 958, 978, 1004, 1045, 1082, 1102, 1128, 1169, 1214
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| On the infinite square grid we start at stage 0 with no toothpicks. At stage 1 we place three consecutive toothpicks and two orthogonal toothpicks, as an asymetric cross with four edges of length 1, 2, 3, and 4, then a(1)=5. At stage 2 we place 4 toothpicks. And so on...
The sequence gives the number of toothpicks in the structure after n stages. A160427 (the first differences) gives the number added at the n-th stage. See A139250 for more information about 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
Nathaniel Johnston, Table of n, a(n) for n = 0..455
Nathaniel Johnston, C program for computing terms
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CROSSREFS
| Cf. A139250, A139251, A160740, A160800, A160802, A160808.
Sequence in context: A192746 A081295 A180565 * A059743 A000322 A205539
Adjacent sequences: A160423 A160424 A160425 * A160427 A160428 A160429
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KEYWORD
| nonn
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AUTHOR
| Omar E. Pol (info(AT)polprimos.com), May 25 2009, May 29 2009
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EXTENSIONS
| Terms after a(13) from Nathaniel Johnston (nathaniel(AT)nathanieljohnston.com), Mar 31 2011
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