cp's OEIS Frontend

A245857 Number of preferential arrangements of n labeled elements such that the minimal number of elements per rank equals 4.

%I A245857 #6 Aug 04 2014 13:02:52
%S A245857 1,0,0,0,70,252,420,660,35640,271700,1389388,5137860,79463020,
%T A245857 905649500,7336909980,48400150764,573924746400,7735300382250,
%U A245857 85942063340210,795156908528290,9670781421636258,143772253669334950,1993964186469438950,24015169625528033550
%N A245857 Number of preferential arrangements of n labeled elements such that the minimal number of elements per rank equals 4.
%H A245857 Alois P. Heinz, <a href="/A245857/b245857.txt">Table of n, a(n) for n = 4..400</a>
%F A245857 E.g.f.: 1/(1-Sum_{j>=4} x^j/j!) - 1/(1-Sum_{j>=5} x^j/j!).
%F A245857 a(n) = A232475(n) - A245790(n) = A245732(n,4) - A245732(n,5).
%p A245857 b:= proc(n, k) option remember; `if`(n=0, 1,
%p A245857       add(b(n-j, k)*binomial(n, j), j=k..n))
%p A245857     end:
%p A245857 a:= n-> b(n, 4) -b(n, 5):
%p A245857 seq(a(n), n=4..30);
%Y A245857 Column k=4 of A245733.
%Y A245857 Cf. A232475, A245790, A245732.
%K A245857 nonn
%O A245857 4,5
%A A245857 _Alois P. Heinz_, Aug 04 2014