A280882 Number of set partitions of [n] into exactly four blocks where sizes of distinct blocks are coprime.

1, 10, 20, 245, 56, 2100, 2640, 36795, 8140, 542542, 72436, 3311945, 6050240, 91668080, 2505120, 1972220235, 92327460, 5331136090, 6360277000, 320219686633, 29187262016, 4567704520100, 3125812500200, 39433339579725, 19033980625296, 2173716576665550

Offset

4,2

Links

Table of n, a(n) for n=4..29.

Wikipedia, Coprime integers

Wikipedia, Partition of a set

Crossrefs

Column k=4 of A280880.

Sequence in context: A217318 A239237 A018990 * A335802 A319599 A160479

Adjacent sequences: A280879 A280880 A280881 * A280883 A280884 A280885

Keyword

nonn

Author

Alois P. Heinz, Jan 09 2017

Status

approved