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A220818 Number of rooted binary MUL-trees with n leaves on the label set [5]. 2
5, 15, 75, 495, 3600, 28275, 232500, 1979385, 17287050, 154041450, 1394844375, 12797919900, 118722187125, 1111672312125, 10493033896875, 99734572903680, 953755379940150, 9169941599036475, 88588446263805000, 859511126918229075, 8371534717621838250 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..200

V. P. Johnson, Enumeration Results on Leaf Labeled Trees, Ph. D. Dissertation, Univ. Southern Calif., 2012.

MATHEMATICA

a[n_] := a[n] = If[n < 2, 5 n, If[OddQ[n], 0, (# (1 - #)/2 &)[a[n/2]]] +

Sum[a[i] a[n - i], {i, 1, n/2}]];

Array[a, 25] (* Jean-Fran├žois Alcover, Sep 02 2019, after Alois P. Heinz in A319539 *)

CROSSREFS

Column 5 of A319539.

Sequence in context: A149654 A149655 A032122 * A064678 A088935 A183937

Adjacent sequences:  A220815 A220816 A220817 * A220819 A220820 A220821

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Dec 22 2012

EXTENSIONS

Terms a(11) and beyond from Andrew Howroyd, Sep 23 2018

STATUS

approved

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Last modified November 21 16:04 EST 2019. Contains 329371 sequences. (Running on oeis4.)