%I #6 Aug 04 2014 13:05:23

%S 1,0,0,0,0,0,924,3432,6006,10010,16016,24752,17190264,139729800,

%T 748339320,2910015528,9794896188,30251595066,2396910064472,

%U 33228482071400,291616291666700,2036218597884900,11895959650285620,61536913327513260,1662981928016982300

%N Number of preferential arrangements of n labeled elements such that the minimal number of elements per rank equals 6.

%H Alois P. Heinz, <a href="/A245859/b245859.txt">Table of n, a(n) for n = 6..400</a>

%F E.g.f.: 1/(1-Sum_{j>=6} x^j/j!) - 1/(1-Sum_{j>=7} x^j/j!).

%F a(n) = A245791(n) - A245792(n) = A245732(n,6) - A245732(n,7).

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

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

%p end:

%p a:= n-> b(n, 6) -b(n, 7):

%p seq(a(n), n=6..35);

%Y Column k=6 of A245733.

%Y a(n) = A245791, A245792, A245732.

%K nonn

%O 6,7

%A _Alois P. Heinz_, Aug 04 2014