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A034010
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Number of 2n-step self avoiding closed walks on square grid, restricted to a quadrant and passing through origin.
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2
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0, 1, 2, 6, 20, 74, 300, 1302, 5944, 28266, 139010, 703102, 3641956, 19255106, 103630920, 566522778, 3140130354, 17620845976
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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REFERENCES
| B. Hayes, How to avoid yourself, American Scientist, Vol. 86, Number 4, Jul-August 1998. p. 314-319
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EXAMPLE
| When the number of steps is 8, one of the six closed paths is
0___.
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CROSSREFS
| A subset of the polyominoes with perimeter 2n (A006725), also a subset of A002931. Cf. A000105, A038373.
Sequence in context: A145867 A188144 A150158 * A135588 A150159 A150160
Adjacent sequences: A034007 A034008 A034009 * A034011 A034012 A034013
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KEYWORD
| nonn,hard,walk
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AUTHOR
| Felice Russo (frusso(AT)micron.com)
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EXTENSIONS
| Corrected and extended by David W. Wilson (davidwwilson(AT)comcast.net)
a(16)-a(18) from Alex Chernov (alex65535(AT)rambler.ru), Jan 22 2012
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