A287254 Number of set partitions of [n] such that all absolute differences between least elements of consecutive blocks are <= four.

1, 1, 2, 5, 15, 52, 202, 857, 3933, 19373, 101755, 566712, 3331349, 20592862, 133439286, 903926271, 6385918342, 46950260915, 358560107124, 2839638581291, 23285101241537, 197425160416845, 1728548417051752, 15610025975013920, 145242705457704688

Offset

0,3

Links

Alois P. Heinz, Table of n, a(n) for n = 0..584

Wikipedia, Partition of a set

Formula

a(n) = A287216(n,4).

a(n) = A000110(n) for n <= 5.

Crossrefs

Column k=4 of A287216.

Cf. A000110.

Sequence in context: A380645 A056272 A140980 * A220912 A108304 A220913

Adjacent sequences: A287251 A287252 A287253 * A287255 A287256 A287257

Keyword

nonn

Author

Alois P. Heinz, May 22 2017

Status

approved