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%I #7 Feb 24 2019 15:05:29
%S 0,1,15,193,2479,33081,464807,6906257,108589887,1805179321,
%T 31676392519,585609896433,11383428770303,232204651095353,
%U 4961029124266599,110811507291845521,2583228239189752447,62748345739947178617,1585780756628964990407,41635723030339339863281
%N Total number of occurrences of 7 in the (signed) displacement sets of all permutations of [n+7] divided by 7!.
%H Alois P. Heinz, <a href="/A324357/b324357.txt">Table of n, a(n) for n = 0..444</a>
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Permutation">Permutation</a>
%F E.g.f.: (1-exp(-x))/(1-x)^8.
%F a(n) = -1/7! * Sum_{j=1..n} (-1)^j * binomial(n,j) * (n+7-j)!.
%F a(n) = A306234(n+7,7).
%p a:= n-> (k-> -add((-1)^j*binomial(n, j)*(n+k-j)!, j=1..n)/k!)(7):
%p seq(a(n), n=0..23);
%Y Column k=7 of A324362.
%Y Cf. A306234.
%K nonn
%O 0,3
%A _Alois P. Heinz_, Feb 23 2019