A001430 Number of graphs with n nodes and n-2 edges.

0, 1, 1, 2, 4, 9, 21, 56, 148, 428, 1305, 4191, 14140, 50159, 185987, 720298, 2905512, 12180208, 52951701, 238253067, 1107432714, 5308573473, 26202267612, 132977762151, 692996060768

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• nice
• easy

Examples

			There are 4 graphs with 5 nodes and 3 edges.
		

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

Crossrefs

Cf. A008406, where this is a diagonal.

Programs

Mathematica

(* first do *) Needs["Combinatorica`"] (* then *) Table[ NumberOfGraphs[n, n-2], {n, 2, 25}] (* Robert G. Wilson v *)

Extensions

More terms from Vladeta Jovovic, Jan 13 2000