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A007169 Number of Q-graphs rooted at a polygon.
(Formerly M1865)
1
0, 1, 2, 8, 43, 283, 1946, 14010, 103292, 776784, 5931402, 45870248, 358501321, 2827227425, 22469524972, 179785568562, 1447059691048, 11708296894260, 95176461591230, 776935668014674, 6366225809581766, 52344041948585714 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

REFERENCES

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

LINKS

Table of n, a(n) for n=1..22.

R. C. Read, On the enumeration of a class of plane multigraphs, Aequat. Math. 31 (1986) no 1, 47-63.

FORMULA

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

CROSSREFS

Cf. A003168.

Sequence in context: A020023 A027836 A326561 * A106327 A009309 A276497

Adjacent sequences:  A007166 A007167 A007168 * A007170 A007171 A007172

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

EXTENSIONS

a(9) corrected and more terms from Sean A. Irvine, Nov 07 2017

STATUS

approved

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Last modified January 28 06:29 EST 2020. Contains 331317 sequences. (Running on oeis4.)