A120699 Lengths of set partitions.

0, 1, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6

Offset

0,3

Comments

Each n occurs Bell(n) times.

Links

Paolo Xausa, Table of n, a(n) for n = 0..10000

Formula

Sum_{n>=1} (-1)^(n+1)/a(n) = Pi/(6*sqrt(3)) + log(3)/2. - Amiram Eldar, Feb 18 2024

Mathematica

Flatten[Array[PadRight[{}, BellB[#], #]&, 7, 0]] (* Paolo Xausa, Feb 13 2024 *)

Crossrefs

Cf. A000110, A120698.

Sequence in context: A251547 A084320 A161358 * A072643 A130260 A276621

Adjacent sequences: A120696 A120697 A120698 * A120700 A120701 A120702

Keyword

nonn

Author

Franklin T. Adams-Watters, Jun 28 2006

Status

approved