login
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
OFFSET
7,8
LINKS
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.
Sequence in context: A290290 A024751 A024759 * A177307 A140911 A351486
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Aug 04 2014
STATUS
approved