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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

Alois P. Heinz, Table of n, a(n) for n = 0..3501

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

Cf. A000081, A004111, A303023.

Sequence in context: A000621 A191317 A218020 * A039828 A246360 A005627

Adjacent sequences:  A318517 A318518 A318519 * A318521 A318522 A318523

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Aug 28 2018

STATUS

approved

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Last modified April 20 08:54 EDT 2021. Contains 343125 sequences. (Running on oeis4.)