This is the unique primitive strongly regular graph on 9 vertices. It has parameters $(9,4,1,2)$. It is self-complementary, like any Paley graph. It is the first subconstituent of the complement of the Hamming graph $H(2,4)$. It is also the first subconstituent of the Johnson graph $J(6,3)$.
| Number of vertices: | $9$ |
| Diameter: | $2$ |
| Intersection array: | $\{4,2; 1,2\}$ |
| Spectrum: | $4^1 1^4 (-2)^4$ |
| Automorphism group: | $\mathrm{S}_3\mathrm{Wr}\mathbb{Z}_2$ |
| Distance-transitive: | Yes |
| Primitive |