A275781 Number of set partitions of [n] having at least two blocks with equal element sums.

0, 0, 0, 1, 3, 9, 43, 209, 1042, 5682, 32875, 200919, 1299092, 8848623, 63108778, 471509591, 3671980053

Offset

0,5

Links

Table of n, a(n) for n=0..16.

Formula

a(n) = A000110(n) - A275780(n).

Example

a(3) = 1: 12|3
a(4) = 3: 12|3|4, 13|2|4, 14|23.
a(5) = 9: 12|3|45, 12|3|4|5, 13|25|4, 13|2|4|5, 14|23|5, 1|23|4|5, 14|2|3|5, 15|24|3, 1|25|34.

Crossrefs

Cf. A000110, A035470, A275780.

Sequence in context: A141774 A141349 A018427 * A199140 A154606 A369387

Adjacent sequences: A275778 A275779 A275780 * A275782 A275783 A275784

Keyword

nonn,more

Author

Alois P. Heinz, Aug 08 2016

Status

approved