Degree-diameter problem $N(15,6)$
The largest possible number of vertices in a graph of maximum degree $15$ and diameter $6$.
Lower bound:
$1417248$
(1,417,248)
Upper bound:
Unknown
Updates
-
1985
Lower bound: $1417248$
(1,417,248)
Gómez, José; Fiol, Miquel (1985), Dense compound graphs, Ars Combinatoria, 20: 211-237
[via Table of the largest known graphs of a given diameter and maximal degree - Wikipedia]