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Number of Q-graphs rooted at a polygon.
(Formerly M1865)
1

%I M1865 #15 Nov 08 2017 02:25:05

%S 0,1,2,8,43,283,1946,14010,103292,776784,5931402,45870248,358501321,

%T 2827227425,22469524972,179785568562,1447059691048,11708296894260,

%U 95176461591230,776935668014674,6366225809581766,52344041948585714

%N Number of Q-graphs rooted at a polygon.

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H R. C. Read, <a href="http://dx.doi.org/10.1007/BF02188172">On the enumeration of a class of plane multigraphs</a>, Aequat. Math. 31 (1986) no 1, 47-63.

%F G.f. Sum_{r >= 2} Z(C_{2*r}; B(x)) where Z(C_{2*r}) is the cycle index of the cyclic group C_{2*r} and B(x) is the g.f. for A003168. - _Sean A. Irvine_, Nov 07 2017

%Y Cf. A003168.

%K nonn

%O 1,3

%A _N. J. A. Sloane_.

%E a(9) corrected and more terms from _Sean A. Irvine_, Nov 07 2017