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A006905 Number of transitive relations on n labeled nodes.
(Formerly M2065)
+0
5
1, 2, 13, 171, 3994, 154303, 9415189, 878222530, 122207703623, 24890747921947, 7307450299510288, 3053521546333103057, 1797003559223770324237, 1476062693867019126073312, 1679239558149570229156802997, 2628225174143857306623695576671, 5626175867513779058707006016592954 (list; graph; listen)
OFFSET

0,2

REFERENCES

D. Ford and J. McKay, personal communication, 1991.

Klaska (1997), Transitivity and Partial Order, Mathematica Bohemica, 122 (1), 75-82. Based on a correspondence between transitive relations and partial orders, the author obtains a formula and calculates the first 14 terms - Jeff McSweeney (jmcsween(AT)mtsu.edu), May 13, 2000

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

S. R. Finch, Transitive relations, topologies and partial orders

G. Pfeiffer, Counting Transitive Relations, Journal of Integer Sequences, Vol. 7 (2004), Article 04.3.2.

CROSSREFS

Cf. A000595, A001173. See A091073 for unlabeled case.

Sequence in context: A078363 A143851 A088316 this_sequence A119400 A137610 A073178

Adjacent sequences: A006902 A006903 A006904 this_sequence A006906 A006907 A006908

KEYWORD

nonn,nice

AUTHOR

Simon Plouffe, N. J. A. Sloane (njas(AT)research.att.com).

EXTENSIONS

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 28 2003

2 more terms from Charles R. Greathouse IV Aug 30 2006

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Last modified December 17 13:29 EST 2009. Contains 170826 sequences.


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