The 231-Cameron graph is a strongly regular Hamiltonian graph on 231 vertices
with parameters 
.
It is distance-regular with intersection
array 
,
but is not distance-transitive.
It is named after mathematician Peter J. Cameron (Cameron et al. 1978).
It can be constructed by taking as vertices the 
unordered pairs from the point
set of the Steiner system 
and joining two vertices
when the pairs are disjoint and their union
is contained in a block (Brouwer and van Lint 1984).
It has graph spectrum 
, and is therefore an integral
graph. It has graph automorphism group order 
.
It is a Hamiltonian graph.
The 231-Cameron graph is implemented in the Wolfram Language as GraphData["CameronGraph"]. It should not be confused with the Cameron cubic Hamiltonian graphs constructed by Kathleen Cameron, or with the Cameron-Montanaro-Newman-Severini-Winter graph, an 18-vertex graph related to the quantum chromatic number.
