A123422 - OEIS

A123422

Number of elementary graphs on n nodes.

1, 2, 4, 10, 25, 79, 253, 936, 3601, 15486, 74413, 441436, 3505441, 40309116, 670660262

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

OFFSET

1,2

COMMENTS

A graph is called elementary if its edges can be colored with two colors such that no monochromatic induced P_3 occurs. Elementary graphs are perfect. - Falk Hüffner, Jun 30 2018

LINKS

Table of n, a(n) for n=1..15.

S. Hougardy, Classes of perfect graphs, Discr. Math. 306 (2006), 2529-2571.

F. Hüffner, tinygraph, software for generating integer sequences based on graph properties, version 6c1dbe4.

CROSSREFS

Sequence in context: A124419 A148096 A006901 * A123413 A085633 A111564

Adjacent sequences: A123419 A123420 A123421 * A123423 A123424 A123425

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Oct 18 2006

EXTENSIONS

a(11)-a(15) added using tinygraph by Falk Hüffner, Jun 30 2018

STATUS

approved