%I A003286 M4441
%S A003286 1,7,66,916,16816
%N A003286 Number of semi-regular digraphs on n nodes.
%D A003286 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A003286 Choudum, S. A.; Parthasarathy, K. R. Semi-regular relations and digraphs. 
               Nederl. Akad. Wetensch. Proc. Ser. A. {75}=Indag. Math. 34 (1972), 
               326-334.
%Y A003286 Sequence in context: A065097 A122705 A024395 this_sequence A052351 A106111 
               A142786
%Y A003286 Adjacent sequences: A003283 A003284 A003285 this_sequence A003287 A003288 
               A003289
%K A003286 nonn,nice,more
%O A003286 2,2
%A A003286 N. J. A. Sloane (njas(AT)research.att.com).