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A019275
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Number of rooted prime binary trees (those which are not products).
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0
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1, 2, 4, 38, 132, 420, 1426, 4834, 16796, 58688, 208012, 742636, 2674384, 9693976, 35357670, 129641774
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| See A035010 for definition.
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REFERENCES
| V. Blondel, Operations on binary trees, Comptes Rendus de l'Academie des Sciences de Paris - Serie I, 321, 491-494, 1995.
V. Blondel, Structured numbers: properties of a hierarchy of operations on binary trees, Acta Informatica, vol. 35 (1998), pp. 1-15.
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LINKS
| Index entries for sequences related to rooted trees
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CROSSREFS
| Sequence in context: A018304 A051692 A053745 * A012433 A012438 A009626
Adjacent sequences: A019272 A019273 A019274 * A019276 A019277 A019278
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KEYWORD
| nonn,nice
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AUTHOR
| Vincent Blondel (blondel(AT)ulg.ac.be)
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