A151338 Triangle read by rows: T(n,k) = number of partitions of [1..k] into n nonempty clumps of sizes 1, 2, 3, 4 or 5 (n >= 0, 0 <= k <= 5n).

1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 3, 7, 15, 31, 56, 91, 126, 126, 0, 0, 0, 1, 6, 25, 90, 301, 938, 2737, 7455, 18711, 41811, 81081, 126126, 126126, 0, 0, 0, 0, 1, 10, 65, 350, 1701, 7686, 32725, 132055, 505351, 1824823, 6173167, 19339320, 55096041

Offset

0,11

Comments

Row n has 5n+1 entries.

Links

Table of n, a(n) for n=0..50.

Moa Apagodu, David Applegate, N. J. A. Sloane, and Doron Zeilberger, Analysis of the Gift Exchange Problem, arXiv:1701.08394, 2017.

David Applegate and N. J. A. Sloane, The Gift Exchange Problem (arXiv:0907.0513, 2009)

Example

The triangle begins:
1
0, 1, 1, 1, 1, 1
0, 0, 1, 3, 7, 15, 31, 56, 91, 126, 126
0, 0, 0, 1, 6, 25, 90, 301, 938, 2737, 7455, 18711, 41811, 81081, 126126, 126126
0, 0, 0, 0, 1, 10, 65, 350, 1701, 7686, 32725, 132055, 505351, 1824823, 6173167, 19339320, 55096041, 138654516, 295891596, 488864376, 488864376
0, 0, 0, 0, 0, 1, 15, 140, 1050, 6951, 42315, 241780, 1310925, 6782776, 33549516, 158533375, 713733020, 3046944901, 12246267033, 45892143297, 158167994985, 491492022021, 1336310771796, 3030225834636, 5194672859376, 5194672859376
...

Crossrefs

This is one of a sequence of triangles: A144331, A144385, A144643, A151338, A151359, ...

See A151509, A151510 for other versions.

Sequence in context: A137170 A222813 A304078 * A229006 A023424 A276647

Adjacent sequences: A151335 A151336 A151337 * A151339 A151340 A151341

Keyword

nonn,tabf

Author

N. J. A. Sloane, May 13 2009

Status

approved