%I A003088 M2011
%S A003088 1,1,2,11,171,8603,1478644
%N A003088 Number of unilateral digraphs with n unlabeled nodes.
%D A003088 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A003088 F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 
               1973, p. 218.
%D A003088 R. C. Read (rcread(AT)math.uwaterloo.ca), email to N. J. A. Sloane (njas(AT)research.att.com), 
               28 August, 2000.
%D A003088 R. C. Read and R. J. Wilson, An Atlas of Graphs, Oxford, 1998.
%D A003088 R. W. Robinson, Counting strong digraphs (research announcement), J. 
               Graph Theory 1, 1977, pp. 189-190.
%Y A003088 Cf. A057270, A003029 (labeled case), A003085, A035512, A051421, A049531, 
               A049512.
%Y A003088 Sequence in context: A013050 A051255 A120445 this_sequence A121231 A122527 
               A039747
%Y A003088 Adjacent sequences: A003085 A003086 A003087 this_sequence A003089 A003090 
               A003091
%K A003088 nonn,nice,more
%O A003088 0,3
%A A003088 N. J. A. Sloane (njas(AT)research.att.com).
%E A003088 Note that Read and Wilson incorrectly give a(4) as 172 - thanks to Vladeta 
               Jovovic, Goran Kilibarda (vladeta(AT)eunet.rs) for finding this error 
               and for verifying a(5).