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A245857 Number of preferential arrangements of n labeled elements such that the minimal number of elements per rank equals 4. 2
1, 0, 0, 0, 70, 252, 420, 660, 35640, 271700, 1389388, 5137860, 79463020, 905649500, 7336909980, 48400150764, 573924746400, 7735300382250, 85942063340210, 795156908528290, 9670781421636258, 143772253669334950, 1993964186469438950, 24015169625528033550 (list; graph; refs; listen; history; text; internal format)
OFFSET
4,5
LINKS
FORMULA
E.g.f.: 1/(1-Sum_{j>=4} x^j/j!) - 1/(1-Sum_{j>=5} x^j/j!).
a(n) = A232475(n) - A245790(n) = A245732(n,4) - A245732(n,5).
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, 4) -b(n, 5):
seq(a(n), n=4..30);
CROSSREFS
Column k=4 of A245733.
Sequence in context: A235303 A234564 A234557 * A227879 A072596 A309310
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Aug 04 2014
STATUS
approved

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Last modified July 14 13:00 EDT 2024. Contains 374318 sequences. (Running on oeis4.)