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A318520
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Number of unlabeled rooted identity trees with n non-binary nodes.
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2
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0, 1, 1, 1, 1, 1, 1, 2, 3, 5, 8, 14, 23, 40, 69, 122, 215, 382, 679, 1217, 2185, 3944, 7136, 12958, 23578, 43026, 78673, 144190, 264755, 487074, 897549, 1656697, 3062423, 5669110, 10508397, 19503447, 36240898, 67418514, 125551221, 234047825, 436722486
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listen;
history;
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internal format)
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OFFSET
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0,8
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LINKS
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Alois P. Heinz, Table of n, a(n) for n = 0..3501
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EXAMPLE
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a(8) = 3: o o o
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o o o o o
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o o o o o o
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o o o o
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o o o
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o
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o
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o
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MAPLE
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b:= proc(n, i, t) option remember; `if`(n=0, `if`(t=1, 0, 1), `if`(i<1, 0,
add(b(n-i*j, i-1, max(0, t-j))*binomial(a(i), j), j=0..n/i)))
end:
a:= n-> `if`(n<2, n, b(n-1$2, 3)):
seq(a(n), n=0..50);
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CROSSREFS
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Cf. A000081, A004111, A303023.
Sequence in context: A000621 A191317 A218020 * A039828 A246360 A005627
Adjacent sequences: A318517 A318518 A318519 * A318521 A318522 A318523
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KEYWORD
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nonn
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AUTHOR
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Alois P. Heinz, Aug 28 2018
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STATUS
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approved
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