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A259114 Number of rooted binary unordered tanglegrams of size n. 6
1, 1, 2, 10, 69, 807, 13048, 269221, 6660455, 191411477, 6257905519, 229312906604, 9309547057292, 414803750101863 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
Binary tanglegrams are pairs of bifurcating (degree 3 internal node) trees with a bijection between the leaves of the trees. Two tanglegrams are isomorphic if there is an isomorphism between the trees that preserves the bijection. Rooted means that the tanglegram is composed of rooted trees, and unordered means that two tanglegrams that differ by exchanging the trees and inverting the bijection are considered identical.
LINKS
S. C. Billey, M. Konvalinka, and F. A. Matsen IV, On the enumeration of tanglegrams and tangled chains, arXiv:1507.04976 [math.CO], 2015.
Ira M. Gessel, Counting tanglegrams with species, arXiv:1509.03867 [math.CO], (13-September-2015)
F. A. Matsen IV, S. C. Billey, D. A. Kas, and M. Konvalinka, Tanglegrams: a reduction tool for mathematical phylogenetics, arXiv:1507.04784 [q-bio.PE], 2015.
CROSSREFS
Cf. A258620 (tanglegrams), A259115, A259116, A258486 (tangled chains), A258487, A258488, A258489.
Sequence in context: A325054 A139715 A293914 * A051575 A121201 A166076
KEYWORD
nonn,more
AUTHOR
EXTENSIONS
More terms from Ira M. Gessel, Jul 19 2015
STATUS
approved

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Last modified February 27 19:09 EST 2024. Contains 370378 sequences. (Running on oeis4.)