This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A007140 M2980 #23 Sep 25 2018 18:44:30 %S A007140 1,1,3,14,115,2086,101791,14835870,6852422567,10338780759514, %T A007140 51804974736769271,872530598196790164797,49930445153769776449253479, %U A007140 9805619466642079028742952893709,6670375074613812276139335045628924297,15853216549413764390038207575938343994222273 %N A007140 Number of unlabeled bicolored graphs, with no isolated nodes, on 2n nodes having n nodes of each color and allowing the color classes to be interchanged. %D A007140 R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1976. %D A007140 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A007140 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 A007140 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] %F A007140 a(n) = (A054976(n) + A319155(n)) / 2. - _Andrew Howroyd_, Sep 25 2018 %Y A007140 Row sums of A123547. %Y A007140 Cf. A007139, A054976, A319155. %K A007140 nonn %O A007140 0,3 %A A007140 _N. J. A. Sloane_ %E A007140 a(11)-a(15) from _Andrew Howroyd_, Sep 25 2018