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A245860 Number of preferential arrangements of n labeled elements such that the minimal number of elements per rank equals 7. 2
1, 0, 0, 0, 0, 0, 0, 3432, 12870, 22880, 38896, 63648, 100776, 155040, 399305520, 3292693008, 17879790324, 70676513424, 242216077400, 762341522800, 2264840592300, 478970960616720, 6869326015894680, 61426122596911800, 435982960069722000, 2589856033041531072 (list; graph; refs; listen; history; text; internal format)
OFFSET

7,8

LINKS

Alois P. Heinz, Table of n, a(n) for n = 7..400

FORMULA

E.g.f.: 1/(1-Sum_{j>=7} x^j/j!) - 1/(1-Sum_{j>=8} x^j/j!).

a(n) = A245792(n) - A245793(n) = A245732(n,7) - A245732(n,8).

MAPLE

b:= proc(n, k) option remember; `if`(n=0, 1,

add(b(n-j, k)*binomial(n, j), j=k..n))

end:

a:= n-> b(n, 7) -b(n, 8):

seq(a(n), n=7..35);

CROSSREFS

Column k=7 of A245733.

Cf. A245792, A245793, A245732.

Sequence in context: A290290 A024751 A024759 * A177307 A140911 A351486

Adjacent sequences: A245857 A245858 A245859 * A245861 A245862 A245863

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Aug 04 2014

STATUS

approved

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Last modified January 28 22:08 EST 2023. Contains 359905 sequences. (Running on oeis4.)