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, 29797471739, 251120234182, 2196428139810, 19882638695048, 186205573812059, 1799766634300161, 17946783669353462, 184277407872729741, 1947501874827169041

Offset: 0

Author

Alois P. Heinz, Aug 08 2016

Keywords

• nonn

Examples

			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.

Formula

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

Extensions

a(17)-a(25) from Christian Sievers, Aug 20 2024