A006647 Number of graphs with n nodes, n-2 edges and no isolated vertices. (Formerly M2586)

1, 1, 3, 6, 15, 33, 83, 202, 527, 1377, 3744, 10335, 29297, 84396, 248034, 740289, 2245094, 6904206, 21522973, 67936799, 217026480, 701159919, 2289925258, 7556363054, 25184139149, 84743377436, 287815771822, 986345040471, 3409869008578

Offset

4,3

References

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

Links

Table of n, a(n) for n=4..32.

W. L. Kocay, Some new methods in reconstruction theory, pp. 89 - 114 of Combinatorial Mathematics IX. Proc. Ninth Australian Conference (Brisbane, August 1981). Ed. E. J. Billington, S. Oates-Williams and A. P. Street. Lecture Notes Math., 952. Springer-Verlag, 1982.

Formula

a(n) = A001430(n) - A001433(n - 1). - Sean A. Irvine, Jun 05 2017

Crossrefs

Cf. A001430, A001433.

Sequence in context: A105476 A000599 A063832 * A032126 A190525 A032176

Adjacent sequences: A006644 A006645 A006646 * A006648 A006649 A006650

Keyword

nonn

Author

N. J. A. Sloane.

Extensions

More terms from Vladeta Jovovic, Mar 02 2008

More terms from Sean A. Irvine, Jun 05 2017

Status

approved