[seqfan] Re: labeled digraphs in A214398
Richard J. Mathar
mathar at mpia-hd.mpg.de
Fri Aug 4 10:19:21 CEST 2017
In response to http://list.seqfan.eu/pipermail/seqfan/2017-August/017837.html :
this observation is trivial. The number of vertex-labeled digraphs
with E arcs and V vertices without restrictions on loops or multi-edges
is the number of ways of distributing the E arcs over the V^2 in
the adjancy matrix.
The weak compositions are by standard combinatorics binomial(V^2+E-1,E-1).
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