A275074 Number of set partitions of [n] such that i-j is a multiple of seven for all i,j belonging to the same block.

1, 1, 1, 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 128, 320, 800, 2000, 5000, 12500, 31250, 78125, 234375, 703125, 2109375, 6328125, 18984375, 56953125, 170859375, 592312500, 2053350000, 7118280000, 24676704000, 85545907200, 296559144960, 1028071702528

Offset: 0

Author

Alois P. Heinz, Jul 15 2016

Keywords

• nonn

Examples

			a(9) = 4: 18|29|3|4|5|6|7, 18|2|3|4|5|6|7|9, 1|29|3|4|5|6|7|8, 1|2|3|4|5|6|7|8|9.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..826
• Wikipedia, Partition of a set

Crossrefs

Column k=7 of A275069.

Cf. A000110.

Formula

a(n) = Product_{i=0..6} A000110(floor((n+i)/7)).