Search: id:A001174
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%I A001174 M1809 N0715
%S A001174 1,2,7,42,582,21480,2142288,575016219,415939243032,816007449011040,
%T A001174 4374406209970747314,64539836938720749739356,
%U A001174 2637796735571225009053373136,300365896158980530053498490893399
%N A001174 Number of oriented graphs (i.e. digraphs with no bidirected edges) on 
               n unlabeled nodes. Also number of complete digraphs on n unlabeled 
               nodes. Number of antisymmetric relations (i.e. oriented graphs with 
               loops) on n unlabeled nodes is A083670.
%D A001174 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A001174 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A001174 R. L. Davis, The number of structures of finite relations, Proc. Amer. 
               Math. Soc. 4 (1953), 486-495.
%D A001174 F. Harary and E. M. Palmer, Enumeration of mixed graphs, Proc. Amer. 
               Math. Soc., 17 (1966), 682-687.
%D A001174 F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 
               1973, p. 133, c_p.
%D A001174 M. D. McIlroy, Calculation of numbers of structures of relations on finite 
               sets, Massachusetts Institute of Technology, Research Laboratory 
               of Electronics, Quarterly Progress Reports, No. 17, Sept. 15, 1955, 
               pp. 14-22.
%H A001174 P. J. Cameron, <a href="http://www.cs.uwaterloo.ca/journals/JIS/index.html">
               Sequences realized by oligomorphic permutation groups</a>, J. Integ. 
               Seqs. Vol. 3 (2000), #00.1.5.
%H A001174 G. Pfeiffer, <a href="http://www.cs.uwaterloo.ca/journals/JIS/">Counting 
               Transitive Relations</a>, Journal of Integer Sequences, Vol. 7 (2004), 
               Article 04.3.2.
%H A001174 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               OrientedGraph.html">Oriented Graph</a>
%F A001174 There's an explicit formula - see for example Harary and Palmer (book), 
               Eq. (5.4.14).
%Y A001174 Cf. A000595, A001173.
%Y A001174 Cf. A047656 (labeled case), A054941 (connected labeled case), A086345 
               (connected unlabeled case).
%Y A001174 Sequence in context: A091669 A108042 A152559 this_sequence A067975 A065298 
               A091877
%Y A001174 Adjacent sequences: A001171 A001172 A001173 this_sequence A001175 A001176 
               A001177
%K A001174 nonn,nice,easy
%O A001174 1,2
%A A001174 N. J. A. Sloane (njas(AT)research.att.com).
%E A001174 More terms from Vladeta Jovovic (vladeta(AT)eunet.rs)
%E A001174 Revised description from Vladeta Jovovic (vladeta(AT)eunet.rs), Jan 20 
               2005

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