Degree-diameter problem $N(15,5)$

The largest possible number of vertices in a graph of maximum degree $15$ and diameter $5$ .

Lower bound: $77520$ (77,520)
Upper bound: Unknown

Updates

2008 Lower bound: $76518$ (76,518)
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: $77520$ (77,520)
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]