|
%I
%S 1,0,0,0,70,252,420,660,35640,271700,1389388,5137860,79463020,
%T 905649500,7336909980,48400150764,573924746400,7735300382250,
%U 85942063340210,795156908528290,9670781421636258,143772253669334950,1993964186469438950,24015169625528033550
%N Number of preferential arrangements of n labeled elements such that the minimal number of elements per rank equals 4.
%H Alois P. Heinz, <a href="/A245857/b245857.txt">Table of n, a(n) for n = 4..400</a>
%F E.g.f.: 1/(1-Sum_{j>=4} x^j/j!) - 1/(1-Sum_{j>=5} x^j/j!).
%F a(n) = A232475(n) - A245790(n) = A245732(n,4) - A245732(n,5).
%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, 4) -b(n, 5):
%p seq(a(n), n=4..30);
%Y Column k=4 of A245733.
%Y Cf. A232475, A245790, A245732.
%K nonn
%O 4,5
%A _Alois P. Heinz_, Aug 04 2014
|
