

A123467


Number of triviallyperfect graphs on n nodes.


4



1, 2, 4, 9, 20, 48, 115, 286, 719, 1842, 4766, 12486, 32973, 87811, 235381, 634847, 1721159, 4688676, 12826228, 35221832, 97055181, 268282855, 743724984, 2067174645, 5759636510, 16083734329, 45007066269, 126186554308, 354426847597
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OFFSET

1,2


COMMENTS

Is this the same as A000081 with a different offset?  N. J. A. Sloane
Yes, because it equals the number of rooted forests with n nodes (see Golumbic reference). The Euler transform shifts this sequence by one. Thus the number of connected triviallyperfect graphs on n nodes is a(n1).  Falk Hüffner, Nov 26 2015


LINKS

Table of n, a(n) for n=1..29.
M. C. Golumbic, Trivially perfect graphs, Discr. Math. 24(1) (1978), 105107.
S. Hougardy, Home Page
S. Hougardy, Classes of perfect graphs, Discr. Math. 306 (2006), 25292571.


FORMULA

a(n) = A000081(n+1)  Falk Hüffner, Nov 26 2015


CROSSREFS

Cf. A000081.
Sequence in context: A292556 A145550 A000081 * A124497 A286983 A289971
Adjacent sequences: A123464 A123465 A123466 * A123468 A123469 A123470


KEYWORD

nonn


AUTHOR

N. J. A. Sloane, Oct 18 2006


STATUS

approved



