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A005220
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Number of Dyck paths of knight moves.
(Formerly M2256)
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2
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1, 0, 1, 0, 3, 2, 12, 14, 54, 86, 274, 528, 1515, 3266, 8854, 20422, 53786, 129368, 336103, 830148, 2145020, 5390580, 13913325, 35378586, 91415954, 234397542, 606983495, 1566013450, 4065765499, 10540066710, 27437831060, 71404804002
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,5
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REFERENCES
| J. Labelle and Y.-N. Yeh, Dyck paths of knight moves, Discrete Applied Math., 24 (1989), 213-221.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
| T. D. Noe, Table of n, a(n) for n=0..200
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FORMULA
| G.f.=(1+2z+sqrt(1-4z+4z^2-4z^4)-sqrt(2)*sqrt(1-4z^2-2z^4+(2z+1)sqrt(1-4z+4z^2-4z^4)))/[4z^2].
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CROSSREFS
| Sequence in context: A098646 A129925 A057779 * A152550 A114798 A167639
Adjacent sequences: A005217 A005218 A005219 * A005221 A005222 A005223
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KEYWORD
| nonn,easy,nice
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Dec 17 2003
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