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%I #6 Aug 04 2014 10:59:00
%S 1,2,12,68,520,4542,46550,540136,7045020,101865410,1619046418,
%T 28053492348,526430246264,10636085523910,230214619661790,
%U 5314695463338704,130356558777712468,3385311352838750538,92797887464933030762,2677623216872061223780,81123642038690958720048
%N Number of preferential arrangements of n labeled elements such that the minimal number of elements per rank equals 1.
%H Alois P. Heinz, <a href="/A245854/b245854.txt">Table of n, a(n) for n = 1..400</a>
%F E.g.f.: 1/(2-exp(x))-1/(2-exp(x)+x).
%F a(n) = A000670(n) - A032032(n) = A245732(n,1) - A245732(n,2).
%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, 1) -b(n, 2):
%p seq(a(n), n=1..25);
%Y Column k=1 of A245733.
%Y Cf. A000670, A032032, A245732.
%K nonn
%O 1,2
%A _Alois P. Heinz_, Aug 04 2014
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