A007169 Number of Q-graphs rooted at a polygon. (Formerly M1865)

0, 1, 2, 8, 43, 283, 1946, 14010, 103292, 776784, 5931402, 45870248, 358501321, 2827227425, 22469524972, 179785568562, 1447059691048, 11708296894260, 95176461591230, 776935668014674, 6366225809581766, 52344041948585714

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