

A054927


Number of connected unlabeled graphs having n nodes and ceiling(n(n1)/4) edges such that the complement is also connected.


0



1, 0, 0, 1, 4, 17, 122, 1512, 32692, 1332942, 105327842, 15931236010, 4514847754466, 2400986640234092, 2424697785383015323, 4646743375611622382082, 16785578201380816581985232, 114710315501226850209685442155
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,5


COMMENTS

These graphs are called "median graphs" by Liskovets, but that name is more commonly used for the graphs counted in A292623.  Brendan McKay, Apr 14 2019


LINKS

Table of n, a(n) for n=1..18.
V. A. Liskovets, Some easily derivable sequences, J. Integer Sequences, 3 (2000), #00.2.2.


FORMULA

a(n) = A001437(n)+A054926(n)A000717(n).


CROSSREFS

Sequence in context: A206353 A260694 A032115 * A307794 A071138 A032325
Adjacent sequences: A054924 A054925 A054926 * A054928 A054929 A054930


KEYWORD

nonn,more


AUTHOR

N. J. A. Sloane, May 24 2000


EXTENSIONS

Name changed by Brendan McKay, Apr 14 2019
3 more terms by lookup in the 3 seqs of the formula.  R. J. Mathar, May 08 2019


STATUS

approved



