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Number of squarefree graphs on n nodes with maximal number of edges.
5

%I #25 Mar 08 2022 03:29:13

%S 1,1,1,1,1,4,5,5,10,2,11,3,2,1,2,2,1,1,5,1,1,13,1,20,9,8,7,1,2,1,1,9,

%T 18,1,1,5,11

%N Number of squarefree graphs on n nodes with maximal number of edges.

%C Number of squarefree graphs on n nodes with A006855(n) edges.

%H C. R. J. Clapham, A. Flockhart, and J. Sheehan, <a href="https://doi.org/10.1002/jgt.3190130107">Graphs without Four-Cycles</a>, Journal of Graph Theory, 31 (1989), 29-47.

%H D. B. West, A. Bialostocki, and J. Schonheim, <a href="https://www.jstor.org/stable/2324941">E3387 (Large Graphs with No 4-cycle)</a>, The American Mathematical Monthly, 98 (Aug. - Sep. 1991), 653-655.

%e There are 2 squarefree graphs on 10 nodes that have maximal number of edges.

%Y Unlabeled version of A191966.

%Y Cf. A006786, A006855, A077269, A300756.

%K nonn,more

%O 1,6

%A _Jason Zimba_, Jul 22 2020

%E a(22)-a(37) from _Brendan McKay_, Mar 08 2022