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

Author

Alois P. Heinz, Jan 09 2017

Keywords

• nonn

Links

• Wikipedia, Coprime integers
• Wikipedia, Partition of a set

Crossrefs

Column k=4 of A280880.