A000717 Number of graphs with n nodes and floor(n(n-1)/4) edges. (Formerly M2599 N1027)

1, 1, 1, 3, 6, 24, 148, 1646, 34040, 1358852, 106321628, 16006173014, 4525920859198, 2404130854745735, 2426376196165902704, 4648429222263945620900, 16788801124652327714275292, 114722035311851620271616102401

Offset

1,4

Comments

This is the largest number of graphs with n vertices that all have the same number of edges. a(n) <= A371161(n). - Allan Bickle, Apr 18 2024

References

J. Riordan, An Introduction to Combinatorial Analysis, Wiley, 1958, p. 146.

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Sean A. Irvine, Table of n, a(n) for n = 1..40

M. L. Stein and P. R. Stein, Enumeration of Linear Graphs and Connected Linear Graphs up to p = 18 Points. Report LA-3775, Los Alamos Scientific Laboratory of the University of California, Los Alamos, NM, Oct 1967

Example

There are three graphs with 4 vertices and 3 edges, K_3 U K_1, K_{1,3}, and P_4, so a(4) = 3. - Allan Bickle, Apr 18 2024

Crossrefs

Cf. A008406, A371161.

Sequence in context: A294381 A374654 A081072 * A076020 A018994 A018964

Adjacent sequences: A000714 A000715 A000716 * A000718 A000719 A000720

Keyword

nonn,nice

Author

N. J. A. Sloane

Extensions

More terms from Sean A. Irvine, Mar 10 2011

Status

approved