|
|
A220817
|
|
Number of rooted binary MUL-trees with n leaves on the label set [4].
|
|
3
|
|
|
4, 10, 40, 215, 1260, 8010, 53240, 366680, 2590420, 18674660, 136809240, 1015603015, 7622900360, 57753364510, 441081947840, 3392237023425, 26248421645200, 204202630151860, 1596256637347240, 12531697773337965, 98763817012822460, 781102051887068160
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
MATHEMATICA
|
a[n_] := a[n] = If[n < 2, 4 n, If[OddQ[n], 0, (# (1 - #)/2 &)[a[n/2]]] + Sum[a[i] a[n - i], {i, 1, n/2}]];
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|