|
Search: id:A000608
|
|
|
| A000608 |
|
Number of connected partially ordered sets with n unlabeled elements.
(Formerly M2864 N1152)
|
|
+0
5
|
|
| 1, 1, 1, 3, 10, 44, 238, 1650, 14512, 163341, 2360719, 43944974, 1055019099, 32664984238, 1303143553205, 66900392672168, 4413439778321689
(list; graph; listen)
|
|
|
OFFSET
|
0,4
|
|
|
REFERENCES
|
K. K.-H. Butler and G. Markowsky, Enumeration of finite topologies, Proc. 4th S-E Conf. Combin., Graph Theory, Computing, Congress. Numer. 8 (1973), 169-184.
G. Melan\c{c}on, personal communication.
J. A. Wright, There are 718 6-point topologies, quasi-orderings, and transgraphs, Notices Amer. Math. Soc., 17 (1970), p. 646, Abstract #70T-A106.
|
|
LINKS
|
P. J. Cameron, Sequences realized by oligomorphic permutation groups, J. Integ. Seqs. Vol. 3 (2000), #00.1.5.
N. J. A. Sloane, Transforms
Index entries for sequences related to posets
Gunnar Brinkmann and Brendan D. McKay, Counting unlabeled topologies and transitive relations.
|
|
CROSSREFS
|
Inverse Euler transform of A000112.
Sequence in context: A026682 A096804 A113059 this_sequence A009648 A007125 A102911
Adjacent sequences: A000605 A000606 A000607 this_sequence A000609 A000610 A000611
|
|
KEYWORD
|
hard,nonn,nice
|
|
AUTHOR
|
njas, Simon Plouffe, J. A. Wright
|
|
EXTENSIONS
|
More terms from Christian Bower (bowerc(AT)usa.net), who pointed out connection with A000112, Jan 21 1998 and Dec 12 2001
More terms from Vladeta Jovovic (vladeta(AT)Eunet.yu), Jan 04 2006; corrected Jan 15 2006
|
|
|
Search completed in 0.002 seconds
|
