

A091070


Number of automorphism groups of partial orders on n points.


1



1, 1, 2, 3, 6, 8, 16, 21, 41, 57, 103, 140, 276
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

0,3


LINKS

Table of n, a(n) for n=0..12.
G. Pfeiffer, Subgroups.
G. Pfeiffer, Counting Transitive Relations, Journal of Integer Sequences, Vol. 7 (2004), Article 04.3.2.


EXAMPLE

a(3)=3 because of the 5 partial orders on 3 points, 2 have trivial automorphism group, 2 have an automorphism of order 2 and one has the full symmetric group as its automorphism group; thus 3 different (conjugacy classes of) subgroups occur.


CROSSREFS

Cf. A000638 (subgroups of the symmetric group), A000112 (partial orders).
Sequence in context: A047001 A174021 A267007 * A133586 A141348 A029867
Adjacent sequences: A091067 A091068 A091069 * A091071 A091072 A091073


KEYWORD

hard,more,nonn


AUTHOR

Goetz Pfeiffer (goetz.pfeiffer(AT)nuigalway.ie), Jan 21 2004


STATUS

approved



