A204387 Triangle read by rows: T(n,k) (n >= 1, 2 <= k <= n-1) is number of non-crossing trees with k nodes and path-length n.

1, 0, 1, 0, 2, 1, 0, 0, 4, 1, 0, 0, 3, 6, 1, 0, 0, 4, 10, 8, 1, 0, 0, 0, 12, 21, 10, 1, 0, 0, 0, 12, 32, 28, 12, 1, 0, 0, 0, 6, 45

Offset

1,5

Links

Table of n, a(n) for n=1..41.

E. Deutsch and M. Noy, Statistics on non-crossing trees, Discrete Math., 254 (2002), 75-87 (see Th. 6).

Example

Triangle begins:
1
0 1
0 2 1
0 0 4 1
0 0 3 6 1
0 0 4 10 8 1
0 0 0 12 21 10 1
0 0 0 12 32 28 12 1

Crossrefs

Sequence in context: A369195 A065719 A336087 * A110509 A113953 A319574

Adjacent sequences: A204384 A204385 A204386 * A204388 A204389 A204390

Keyword

nonn,tabl,more

Author

N. J. A. Sloane, Jan 17 2012

Status

approved