A275294 Number of set partitions of [2n] with symmetric block size list of length six.

1, 34, 1035, 31346, 958708, 29677572, 929442097, 29416786597, 939795181248, 30273240306244, 982317847204631, 32081167538512119, 1053762976292882820, 34790825470327029730, 1153951843926244071285, 38433994194836318210579, 1284926817226752232868308

Offset: 3

Author

Alois P. Heinz, Jul 22 2016

Keywords

• nonn

Examples

			a(3) = 1: 1|2|3|4|5|6.
a(4) = 34: 12|3|4|5|6|78, 13|2|4|5|6|78, 1|23|4|5|67|8, 1|23|4|5|68|7, 14|2|3|5|6|78, 1|24|3|5|67|8, 1|24|3|5|68|7, 1|2|34|56|7|8, 1|2|34|57|6|8, 1|2|34|58|6|7, 15|2|3|4|6|78, 1|25|3|4|67|8, 1|25|3|4|68|7, 1|2|35|46|7|8, 1|2|35|47|6|8, 1|2|35|48|6|7, 1|2|36|45|7|8, 1|2|37|45|6|8, 1|2|38|45|6|7, 16|2|3|4|5|78, 1|26|3|4|57|8, 1|26|3|4|58|7, 1|2|36|47|5|8, 1|2|36|48|5|7, 1|2|37|46|5|8, 1|2|38|46|5|7, 1|27|3|4|56|8, 1|28|3|4|56|7, 17|2|3|4|5|68, 1|27|3|4|58|6, 1|2|37|48|5|6, 1|2|38|47|5|6, 1|28|3|4|57|6, 18|2|3|4|5|67.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 3..300
• Vaclav Kotesovec, Recurrence (of order 5)
• Wikipedia, Partition of a set

Crossrefs

Bisection of column k=6 of A275281.

Formula

a(n) ~ 2^(2*n - 6) * 3^(2*n - 1/2) / (5*Pi^(3/2)*n^(3/2)). - Vaclav Kotesovec, Aug 02 2016