A051427 Number of strictly Deza graphs with n nodes.

0, 0, 0, 0, 0, 0, 0, 3, 2, 1, 0, 6, 1, 1, 1

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• nice
• hard
• more

Comments

From the Erikson et al. paper: We consider the following generalization of strongly regular graphs. A graph G is a Deza graph if it is regular and the number of common neighbors of two distinct vertices takes on one of two values (not necessarily depending on the adjacency of the two vertices). - Jonathan Vos Post, Jul 06 2008

Links

• M. Erickson, S. Fernando, W. H. Haemers, D. Hardy and J. Hemmeter, Deza graphs: A generalization of strongly regular graph, J. Combinatorial Designs, Vol 7, Issue 6, 395-405, Oct 21, 1999. See also here.
• Sean A. Irvine, Java program (github)

Crossrefs

Cf. A005176, A076434, A076435, A088741.

Extensions

a(14)-a(15) from Sean A. Irvine, Sep 18 2021