The Dutch windmill graph 
, also called a friendship graph, is the graph obtained
by taking 
copies of the cycle graph 
with a vertex in common (Gallian 2007), and therefore corresponds
to the usual windmill graph 
. It is therefore natural to extend the definition
to 
,
consisting of 
copies of 
.
By construction, the Dutch windmill graph 
has anarboricity 
.
Precomputed properties of Dutch windmill graphs are implemented in the Wolfram Language as GraphData[
"DutchWindmill", 
m, n
].
