A275291 Number of set partitions of [n] with symmetric block size list of length seven.

1, 4, 50, 250, 2160, 12256, 91925, 559987, 3939653, 24964844, 170468820, 1104449861, 7440709045, 48835462696, 327230257098, 2164985118201, 14485751773693, 96353703793654, 644984901718337, 4306885857654070, 28868100135841407, 193352040530826181

Offset: 7

Author

Alois P. Heinz, Jul 22 2016

Keywords

• nonn

Examples

			a(8) = 4: 1|2|3|45|6|7|8, 1|2|3|46|5|7|8, 1|2|3|47|5|6|8, 1|2|3|48|5|6|7.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 7..500
• Wikipedia, Partition of a set

Crossrefs

Column k=7 of A275281.

Formula

a(n) ~ 7^(n+1/2) / (5760*Pi^(3/2)*n^(3/2)). - Vaclav Kotesovec, Aug 02 2016