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A277795
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Number of trees with n unlabeled nodes such that all nodes with degree >2 lie on a single path with length equal to the tree's diameter.
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2
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1, 1, 1, 1, 2, 3, 6, 11, 23, 47, 103, 223, 503, 1132, 2602, 5986, 13922, 32433, 75994, 178354, 419945, 990134, 2339033, 5531459
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history;
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OFFSET
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0,5
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COMMENTS
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First differs from A000055 at a(10).
First differs from A130131 at a(10), n >= 1.
The ratio of consecutive terms seems to tend to some limit. - Andrey Zabolotskiy, Dec 12 2016
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LINKS
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Table of n, a(n) for n=0..23.
Andrey Zabolotskiy, Python script for the sequence
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EXAMPLE
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From Andrey Zabolotskiy, Nov 21 2016: (Start)
Three trees that are counted in A000055(10) but not in a(10):
(1)
o o-o-o
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o----o
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o o-o-o
(2)
o-o-o
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o-o-o-o
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o-o-o
(3)
o-o-o-o-o-o-o
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o-o-o
(End)
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CROSSREFS
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Cf. A000055, A130131.
Sequence in context: A359392 A199142 A090344 * A198662 A198620 A198648
Adjacent sequences: A277792 A277793 A277794 * A277796 A277797 A277798
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KEYWORD
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nonn,more
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AUTHOR
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Gabriel Burns, Oct 31 2016
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EXTENSIONS
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Corrections and more terms from Andrey Zabolotskiy, Nov 21 2016
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STATUS
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approved
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