Degree-diameter problem $N(20,9)$
The largest possible number of vertices in a graph of maximum degree $20$ and diameter $9$.
Lower bound:
$12951451931$
(12,951,451,931)
Upper bound:
Unknown
Updates
-
2010-09
Lower bound: $12951451931$
(12,951,451,931)
Loz, E., & Pineda-Villavicencio, G. (2010). New benchmarks for large-scale networks with given maximum degree and diameter. The Computer Journal, 53(7), 1092-1105.
[via The Degree Diameter Problem for General Graphs - Combinatorics Wiki]