Berlekamp–Van Lint–Seidel graph

In graph theory, the Berlekamp–Van Lint–Seidel graph is a locally linear strongly regular graph with parameters ( 243 , 22 , 1 , 2 ) {\displaystyle (243,22,1,2)} . This means that it has 243 vertices, 22 edges per vertex (for a total of 2673 edges), exactly one shared neighbor per pair of adjacent vertices, and exactly two shared neighbors per pair of non-adjacent vertices.