A321526 Number of partitioned graphs on n labeled nodes.

1, 4, 40, 960, 53248, 6651904, 1839202304, 1111322787840, 1453210774536192, 4080507553002291200, 24448060793158379765760, 310908581955001382242091008, 8355018414502495124631718985728, 472643828352464917980832865510752256

Offset

1,2

Comments

Bell numbers (partitions of the nodes) multiplied by the number of graphs on the nodes.

Links

Peter Baumgartner, Table of n, a(n) for n = 1..50

Formula

a(n) = A000110(n) * A006125(n).

a(n) = Bell(n) * 2^binomial(n, 2).

Example

a(1) = 1 * 1; a(2) = 2 * 2, a(3) = 5 * 8, a(4) = 15 * 64.

Mathematica

a[n_] := BellB[n]*2^Binomial[n, 2]; Array[a, 14] (* Amiram Eldar, Nov 12 2018 *)

Prog

(PARI) bell(n)={sum(k=0, n, stirling(n, k, 2))}
a(n)=bell(n)*2^binomial(n, 2) \\ Andrew Howroyd, Nov 12 2018

Crossrefs

Cf. A000110, A006125.

Sequence in context: A211040 A012957 A012977 * A361057 A013108 A173945

Adjacent sequences: A321523 A321524 A321525 * A321527 A321528 A321529

Keyword

nonn

Author

Peter Baumgartner, Nov 12 2018

Status

approved