%I A000683 M4238 N1770
%S A000683 0,1,6,40,360,4576,82656,2122240,77366400,4002843136,293717546496,
%T A000683 30558458490880,4505780560619520,941417163728674816,
%U A000683 278628902101315608576,116805328001281573519360
%N A000683 Number of 2-colored labeled graphs on n nodes.
%D A000683 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A000683 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A000683 F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 
               1973, p. 18, table 1.5.1, column 2 (divided by 2).
%D A000683 R. C. Read, The number of k-colored graphs on labeled nodes, Canad. J. 
               Math., 12 (1960), 410-414.
%D A000683 R. C. Read, personal communication.
%H A000683 T. D. Noe, <a href="b000683.txt">Table of n, a(n) for n=1..50</a>
%F A000683 Reference gives generating function.
%Y A000683 a(n)=(A047863(n)-2)/4. A diagonal of A058843.
%Y A000683 Sequence in context: A083805 A006387 A014481 this_sequence A143342 A084270 
               A053677
%Y A000683 Adjacent sequences: A000680 A000681 A000682 this_sequence A000684 A000685 
               A000686
%K A000683 nonn,nice,easy
%O A000683 1,3
%A A000683 N. J. A. Sloane (njas(AT)research.att.com).
%E A000683 More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Feb 02 2000