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A071213
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Number of labeled planar trees with n nodes such that the root is smaller than all its children.
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0
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1, 4, 34, 436, 7428, 157368, 3980688, 116949600, 3911421600, 146673662400, 6093249563520, 277729608280320, 13778539159795200, 739059210587980800, 42615627311477606400, 2628646012982829772800, 172704619437756321484800
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,2
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REFERENCES
| C. Chauve, S. Dulucq and O. Guibert, Enumeration of some labeled trees, research report RR-1226-99, LaBRI, Bordeaux I University, 1999.
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MAPLE
| n -> 2 * sum((n-1) * (n-2+k)! / (k! * (n-1-k)), k=0 .. n-2) - ((2*n-3)! / (n-2)!);
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CROSSREFS
| Cf. A000312.
Sequence in context: A158839 A145349 A052630 * A052629 A151919 A193099
Adjacent sequences: A071210 A071211 A071212 * A071214 A071215 A071216
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KEYWORD
| easy,nonn
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AUTHOR
| Cedric Chauve (chauve(AT)lacim.uqam.ca), May 16 2002
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