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A245858
Number of preferential arrangements of n labeled elements such that the minimal number of elements per rank equals 5.
2
1, 0, 0, 0, 0, 252, 924, 1584, 2574, 4004, 762762, 6062784, 31868200, 121314312, 399096216, 12936646128, 167685283332, 1429020461484, 9754485257594, 55756633204272, 905519956068420, 14816352889289380, 179362257853420980, 1745771827872126600
OFFSET
5,6
LINKS
FORMULA
E.g.f.: 1/(1-Sum_{j>=5} x^j/j!) - 1/(1-Sum_{j>=6} x^j/j!).
a(n) = A245790(n) - A245791(n) = A245732(n,5) - A245732(n,6).
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, 5) -b(n, 6):
seq(a(n), n=5..30);
CROSSREFS
Column k=5 of A245733.
Sequence in context: A242570 A046379 A250794 * A200884 A275316 A275315
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Aug 04 2014
STATUS
approved