|
| |
|
|
A127534
|
|
Number of jumps in all even trees with 2n edges. An even tree is an ordered tree in which each vertex has an even outdegree. In the preorder traversal of an ordered tree, any transition from a node at a deeper level to a node on a strictly higher level is called a jump.
|
|
0
| |
|
|
0, 1, 9, 65, 442, 2940, 19380, 127281, 834900, 5476185, 35937525, 236030652, 1551652424, 10210456360, 67254204696, 443410005585, 2926078447656, 19325957314755, 127746785056275, 845069382939705, 5594334252541650
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,3
|
|
|
COMMENTS
| The Krandick reference considers jumps in full binary trees.
|
|
|
REFERENCES
| W. Krandick, Trees and jumps and real roots, J. Computational and Applied Math., 162, 2004, 51-55.
|
|
|
FORMULA
| a(n)=(n-1)(4n-3)C(3n,n)/[3(2n+1)(3n-1)].
|
|
|
MAPLE
| seq((n-1)*(4*n-3)*binomial(3*n, n)/3/(2*n+1)/(3*n-1), n=1..24);
|
|
|
CROSSREFS
| Cf. A127535, A127536.
Sequence in context: A055284 A081040 A102902 * A037548 A036731 A020234
Adjacent sequences: A127531 A127532 A127533 * A127535 A127536 A127537
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Emeric Deutsch (deutsch(AT)duke.poly.edu), Jan 19 2007
|
| |
|
|
