cp's OEIS Frontend

A007139 Number of unlabeled bicolored bipartite graphs on 2n nodes having n nodes of each color with no edges between vertices of the same color and allowing the color classes to be interchanged.

%I A007139 M4172 #59 Dec 16 2020 17:51:03
%S A007139 1,2,6,26,192,3014,127757,16853750,7343780765,10733574184956,
%T A007139 52867617324773592,882178116079222400788,50227997322550920824045262,
%U A007139 9837048598740665027344331562224,6681839615514161556535851222043192179,15867777966020615016665849049841756464001994
%N A007139 Number of unlabeled bicolored bipartite graphs on 2n nodes having n nodes of each color with no edges between vertices of the same color and allowing the color classes to be interchanged.
%D A007139 R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1976.
%D A007139 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A007139 Marko Riedel, <a href="/A007139/b007139.txt">Table of n, a(n) for n = 0..30</a>
%H A007139 F. Harary, L. March and R. W. Robinson, <a href="https://doi.org/10.1068/b050031">On enumerating certain design problems in terms of bicolored graphs with no isolates</a>, Environment and Planning, B 5 (1978), 31-43.
%H A007139 F. Harary, L. March and R. W. Robinson, <a href="/A007139/a007139.pdf">On enumerating certain design problems in terms of bicolored graphs with no isolates</a>, Environment and Planning B: Urban Analytics and City Science, 5 (1978), 31-43. [Annotated scanned copy]
%H A007139 Marko Riedel, <a href="https://math.stackexchange.com/questions/1151538/">Cycle indices for K_{n,n} including shuffles and reflections</a>.
%H A007139 Marko Riedel, <a href="/A007139/a007139_4.maple.txt">Maple code for cycle indices of K_{n,n}</a>
%F A007139 a(n) = (A002724(n)+A122082(n))/2. - _Vladeta Jovovic_, Feb 27 2007
%Y A007139 Cf. A007140.
%K A007139 nonn
%O A007139 0,2
%A A007139 _N. J. A. Sloane_
%E A007139 More terms from _Vladeta Jovovic_, Feb 27 2007
%E A007139 Edited by _N. J. A. Sloane_, Aug 14 2007
%E A007139 Name clarified by _Marko Riedel_, Jun 15 2017
%E A007139 More terms from _Marko Riedel_, Jun 16 2017