A275290 Number of set partitions of [n] with symmetric block size list of length five.

1, 3, 22, 86, 470, 2066, 10299, 47503, 229792, 1081851, 5189068, 24671320, 118223765, 565269659, 2713032552, 13022313334, 62644482305, 301600159952, 1454293747517, 7019496361595, 33922782653124, 164099194834163, 794642770006896, 3851565096708617

Offset

5,2

Links

Alois P. Heinz, Table of n, a(n) for n = 5..500

Vaclav Kotesovec, Recurrence (of order 7)

Wikipedia, Partition of a set

Formula

a(n) ~ 5^n / (96*Pi*n). - Vaclav Kotesovec, Aug 02 2016

Example

a(6) = 3: 1|2|34|5|6, 1|2|35|4|6, 1|2|36|4|5.
a(7) = 22: 12|3|4|5|67, 13|2|4|5|67, 1|23|4|56|7, 1|23|4|57|6, 14|2|3|5|67, 1|24|3|56|7, 1|24|3|57|6, 1|2|345|6|7, 1|2|346|5|7, 1|2|347|5|6, 15|2|3|4|67, 1|25|3|46|7, 1|25|3|47|6, 1|2|356|4|7, 1|2|357|4|6, 1|26|3|45|7, 1|27|3|45|6, 16|2|3|4|57, 1|26|3|47|5, 1|2|367|4|5, 1|27|3|46|5, 17|2|3|4|56.

Crossrefs

Column k=5 of A275281.

Sequence in context: A106150 A135836 A004305 * A368478 A277228 A302272

Adjacent sequences: A275287 A275288 A275289 * A275291 A275292 A275293

Keyword

nonn

Author

Alois P. Heinz, Jul 22 2016

Status

approved