A280880 -id:A280880 - cp's OEIS frontend

A280888 Number of set partitions of [n] into exactly ten blocks where sizes of distinct blocks are coprime.

1, 55, 220, 13585, 2002, 365365, 732160, 52971490, 5299580, 1872409682, 99936200, 23179025870, 62214309080, 5550857869040, 12039496832, 261712025228225, 2847305553950, 449212777481325, 340010469598800, 138437940253287675, 2463591280250100, 2996433107369524875

Offset: 10

Alois P. Heinz, Jan 09 2017

nonn

Wikipedia, Coprime integers
Wikipedia, Partition of a set

Column k=10 of A280880.

A280889 Number of set partitions of [2n] into exactly n blocks where sizes of distinct blocks are coprime.

Original entry on oeis.org

1, 1, 4, 75, 56, 6930, 28512, 2849847, 972400, 693870606, 99936200, 63488350926, 475814969280, 166184959669300, 497980728000, 78877488833249175, 1489333512849120, 1116126129558913110, 1597083864660900000, 4467282986266589095530, 107279471180408841600

Offset: 0

Alois P. Heinz, Jan 09 2017

nonn

			a(1) = 1: 12.
a(2) = 4: 123|4, 124|3, 134|2, 1|234.
a(4) = 56 = binomial(8,3): 12345|6|7|8, 12346|5|7|8, 12347|5|6|8, ..., 1|25678|3|4, 1|2|35678|4, 1|2|3|45678.

Wikipedia, Coprime integers
Wikipedia, Partition of a set

Cf. A280880.

a(n) = A280880(2n,n).

cp's OEIS Frontend

A280888 Number of set partitions of [n] into exactly ten blocks where sizes of distinct blocks are coprime.

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