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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. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,9

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..826

Wikipedia, Partition of a set

FORMULA

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

EXAMPLE

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.

CROSSREFS

Column k=7 of A275069.

Cf. A000110.

Sequence in context: A290239 A286834 A290625 * A290687 A290855 A264791

Adjacent sequences:  A275071 A275072 A275073 * A275075 A275076 A275077

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Jul 15 2016

STATUS

approved

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Last modified June 16 14:16 EDT 2021. Contains 345057 sequences. (Running on oeis4.)