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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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,4

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 4 graphs with 5 nodes and 3 edges.

MATHEMATICA

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

CROSSREFS

Cf. A008406, where this is a diagonal.

Sequence in context: A304914 A005217 A148072 * A148073 A057513 A006080

Adjacent sequences: A001427 A001428 A001429 * A001431 A001432 A001433

KEYWORD

nonn,nice,easy

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Vladeta Jovovic, Jan 13 2000

STATUS

approved

URL: https://oeis.org/A001430

⇱ A001430 - OEIS