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A318520 Number of unlabeled rooted identity trees with n non-binary nodes. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,8
LINKS
EXAMPLE
a(8) = 3: o o o
| | /|\
o o o o o
| /|\ | |
o o o o o o
| | | |
o o o o
| | |
o o o
|
o
|
o
|
o
MAPLE
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);
CROSSREFS
Sequence in context: A000621 A191317 A218020 * A039828 A357303 A246360
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Aug 28 2018
STATUS
approved

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Last modified February 20 21:52 EST 2024. Contains 370219 sequences. (Running on oeis4.)