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A280882 Number of set partitions of [n] into exactly four blocks where sizes of distinct blocks are coprime. 1
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified November 27 20:49 EST 2021. Contains 349395 sequences. (Running on oeis4.)