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Search: id:A005221
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| A005221 |
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Number of Dyck paths of knight moves.
(Formerly M2371)
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+0
1
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| 0, 0, 1, 1, 3, 4, 12, 22, 61, 128, 335, 756, 1936, 4580, 11652, 28402, 72209, 179460, 457274, 1151725, 2945129, 7489680, 19228598, 49256157, 126958030, 327072560, 846173899, 2190012371, 5685200054, 14770728584, 38463268482, 100259225816
(list; graph; listen)
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OFFSET
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0,5
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REFERENCES
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J. Labelle and Y.-N. Yeh, Dyck paths of knight moves, Discrete Applied Math., 24 (1989), 213-221.
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FORMULA
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G.f.: z^2*A^2/(1-zA), where A=(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
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Sequence in context: A075220 A075221 A129922 this_sequence A000206 A075223 A071332
Adjacent sequences: A005218 A005219 A005220 this_sequence A005222 A005223 A005224
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KEYWORD
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nonn,easy,nice
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AUTHOR
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njas
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Dec 17 2003
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