Degree-diameter problem $N(9,4)$

The largest possible number of vertices in a graph of maximum degree $9$ and diameter $4$.

Updates

• 2008 Lower bound: $1550$
  Loz, E., & Sirán, J. (2008). New record graphs in the degree-diameter problem. Australasian Journal of Combinatorics, 41, 63.
  [via The Degree Diameter Problem for General Graphs - Combinatorics Wiki]
• 2024-06-27 Lower bound: $1640$
  Comellas, F. (2024). Table of large graphs with given degree and diameter. arXiv preprint arXiv:2406.18994.
  [via Table of the largest known graphs of a given diameter and maximal degree - Wikipedia]