A343278 a(n) = Stirling2(n, ceiling(n/2)).

1, 1, 1, 3, 7, 25, 90, 350, 1701, 6951, 42525, 179487, 1323652, 5715424, 49329280, 216627840, 2141764053, 9528822303, 106175395755, 477297033785, 5917584964655, 26826851689001, 366282500870286, 1672162773483930, 24930204590758260, 114485073343744260

Offset

0,4

Comments

Number of partitions of an n-set into ceiling(n/2) nonempty subsets.

Links

Table of n, a(n) for n=0..25.

Mathematica

Table[StirlingS2[n, Ceiling[n/2]], {n, 0, 25}] (* Amiram Eldar, Apr 20 2021 *)

Prog

(PARI) a(n) = stirling(n, ceil(n/2), 2); \\ Michel Marcus, Apr 20 2021

Crossrefs

Bisection gives A007820 (even part),

Cf. A048993, A129506, A343279.

Sequence in context: A148739 A129084 A287892 * A002870 A096579 A350650

Adjacent sequences: A343275 A343276 A343277 * A343279 A343280 A343281

Keyword

nonn

Author

Peter Luschny, Apr 20 2021

Status

approved