A220818 Number of rooted binary MUL-trees with n leaves on the label set [5].

5, 15, 75, 495, 3600, 28275, 232500, 1979385, 17287050, 154041450, 1394844375, 12797919900, 118722187125, 1111672312125, 10493033896875, 99734572903680, 953755379940150, 9169941599036475, 88588446263805000, 859511126918229075, 8371534717621838250

Offset: 1

Author

N. J. A. Sloane, Dec 22 2012

Keywords

• nonn

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.

Crossrefs

Column 5 of A319539.

Programs

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-François Alcover, Sep 02 2019, after Alois P. Heinz in A319539 *)

Extensions

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