The Paulus graphs are the 15 strongly regular graphs on 25 nodes with parameters
They are implemented in the Wolfram Language as GraphData "Paulus" ,
The Paley graph .
The 25-node Paulus graphs are cospectral , as are the 26-node Paulus graphs, so none of these is determined
by spectrum .
The graph automorphism group order of all
26-node Paulus graphs (namely 120), and is sometimes known as the Paulus-Rozenfeld-Thompson
(or PRT) graph and denoted et al. 2020).
The Paulus graphs are pancyclic .
The integral graphs and identity
graphs .
See also Chang Graphs ,
Cospectral Graphs ,
Determined by Spectrum ,
Paley
Graph ,
Paulus-Rozenfeld-Thompson
Graph ,
Strongly Regular Graph
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References Brouwer, A. E. "Paulus Graphs." http://www.win.tue.nl/~aeb/drg/graphs/Paulus.html . Brouwer, A. E.; Cohen, A. M.; and Neumaier, A. Distance-Regular
Graphs. DistanceRegular.org.
"Paulus graphs (https://www.distanceregular.org/graphs/paulus25.html . DistanceRegular.org.
"Paulus graphs (https://www.distanceregular.org/graphs/paulus26.html . Gyürki,
Š.; Klin, M.; and Ziv-Av, M. "The Paulus-Rozenfeld-Thompson Graph on
26 Vertices Revisited and Related Combinatorial Structures." In Isomorphisms,
Symmetry and Computations in Algebraic Graph Theory: Pilsen, Czech Republic, October
3-7, 2016 Paulus, A. J. L.
"Conference Matrices and Graphs of Order 26." Technische Hogeschool Eindhoven.
Report WSK 73/06, Eindhoven, 1973. Referenced on Wolfram|Alpha Paulus Graphs
Cite this as:
Weisstein, Eric W. "Paulus Graphs." From
MathWorld https://mathworld.wolfram.com/PaulusGraphs.html
Subject classifications More... Less...
and the 10 strongly regular graphs
on 26 nodes with parameters (26, 10, 3, 4).
"Paulus", 
n, i
].
-Paulus graph is isomorphic to
the 25-Paley graph.
-Paulus graph has the largest possible
graph automorphism group order of all
26-node Paulus graphs (namely 120), and is sometimes known as the Paulus-Rozenfeld-Thompson
(or PRT) graph and denoted 
(Gyürki et al. 2020).
-, 
-, and 
-Paulus graphs have the apparently rather unusual property
of being both integral graphs and identity
graphs.
)
(14 graphs, 7 pairs)." [Excludes the 25-Paley graph.] 
)
(10 graphs)."