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A277795 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. 2
1, 1, 1, 1, 2, 3, 6, 11, 23, 47, 103, 223, 503, 1132, 2602, 5986, 13922, 32433, 75994, 178354, 419945, 990134, 2339033, 5531459 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,5
COMMENTS
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
LINKS
Andrey Zabolotskiy, Python script for the sequence
EXAMPLE
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
| |
o----o
| |
o o-o-o
(2)
o-o-o
|
o-o-o-o
|
o-o-o
(3)
o-o-o-o-o-o-o
|
o-o-o
(End)
CROSSREFS
Sequence in context: A359392 A199142 A090344 * A198662 A198620 A198648
KEYWORD
nonn,more
AUTHOR
Gabriel Burns, Oct 31 2016
EXTENSIONS
Corrections and more terms from Andrey Zabolotskiy, Nov 21 2016
STATUS
approved

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Last modified March 28 13:25 EDT 2024. Contains 371254 sequences. (Running on oeis4.)