Degree-diameter problem $N(6,2)$

The largest possible number of vertices in a graph of maximum degree $6$ and diameter $2$ .

Value: $32$

Updates

1977 Lower bound: $32$
Wegner, G. (1977). Graphs with given diameter and a coloring problem.
[via Table of the largest known graphs of a given diameter and maximal degree - Wikipedia]
2006 Upper bound: $32$
Molodtsov, S. G. (2006). Largest graphs of diameter 2 and maximum degree 6. General Theory of Information Transfer and Combinatorics, 853-857.
[via Table of the largest known graphs of a given diameter and maximal degree - Wikipedia]