cp's OEIS Frontend

A245860 Number of preferential arrangements of n labeled elements such that the minimal number of elements per rank equals 7.

%I A245860 #6 Aug 04 2014 13:06:01
%S A245860 1,0,0,0,0,0,0,3432,12870,22880,38896,63648,100776,155040,399305520,
%T A245860 3292693008,17879790324,70676513424,242216077400,762341522800,
%U A245860 2264840592300,478970960616720,6869326015894680,61426122596911800,435982960069722000,2589856033041531072
%N A245860 Number of preferential arrangements of n labeled elements such that the minimal number of elements per rank equals 7.
%H A245860 Alois P. Heinz, <a href="/A245860/b245860.txt">Table of n, a(n) for n = 7..400</a>
%F A245860 E.g.f.: 1/(1-Sum_{j>=7} x^j/j!) - 1/(1-Sum_{j>=8} x^j/j!).
%F A245860 a(n) = A245792(n) - A245793(n) = A245732(n,7) - A245732(n,8).
%p A245860 b:= proc(n, k) option remember; `if`(n=0, 1,
%p A245860       add(b(n-j, k)*binomial(n, j), j=k..n))
%p A245860     end:
%p A245860 a:= n-> b(n, 7) -b(n, 8):
%p A245860 seq(a(n), n=7..35);
%Y A245860 Column k=7 of A245733.
%Y A245860 Cf. A245792, A245793, A245732.
%K A245860 nonn
%O A245860 7,8
%A A245860 _Alois P. Heinz_, Aug 04 2014