A335820 Number of squarefree graphs on n nodes with maximal number of edges.

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, 18, 1, 1, 5, 11

Offset

1,6

Comments

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

Links

Table of n, a(n) for n=1..37.

C. R. J. Clapham, A. Flockhart, and J. Sheehan, Graphs without Four-Cycles, Journal of Graph Theory, 31 (1989), 29-47.

D. B. West, A. Bialostocki, and J. Schonheim, E3387 (Large Graphs with No 4-cycle), The American Mathematical Monthly, 98 (Aug. - Sep. 1991), 653-655.

Example

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

Crossrefs

Unlabeled version of A191966.

Cf. A006786, A006855, A077269, A300756.

Sequence in context: A366166 A154857 A019314 * A195598 A120132 A331263

Adjacent sequences: A335817 A335818 A335819 * A335821 A335822 A335823

Keyword

nonn,more

Author

Jason Zimba, Jul 22 2020

Extensions

a(22)-a(37) from Brendan McKay, Mar 08 2022

Status

approved