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A225824
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The number of increasing rooted identity trees.
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0
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1, 1, 1, 4, 8, 38, 206, 1200, 7034, 53012, 465190, 4072948, 40967916, 438348328, 5113450320, 63135973560, 835727519000, 11736948927176, 175225673352928
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OFFSET
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1,4
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COMMENTS
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Unlabeled rooted identity trees are counted by A004111. An increasing tree is a labeled tree such that any path from the root to each node is increasing.
The first 8 terms are A032301(1..8). The 9th term is A032301(9) plus the 210 increasing labelings of the tree shown in the example.
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LINKS
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Table of n, a(n) for n=1..19.
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EXAMPLE
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There are 210 increasing labelings for this identity tree:
..........0............
........./ \...........
........0 0..........
......./ / \.........
......0 0 0........
...../ | .......
....0 0 .......
.../ .......
..0 .......
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CROSSREFS
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Cf. A032305.
Sequence in context: A208820 A032301 A032213 * A032317 A032226 A001889
Adjacent sequences: A225821 A225822 A225823 * A225825 A225826 A225827
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KEYWORD
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nonn,more
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AUTHOR
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Geoffrey Critzer, Jul 30 2013
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EXTENSIONS
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a(12)-a(19) from Alois P. Heinz, Aug 02 2013
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STATUS
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approved
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