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A006445

Number of n-edge 3-connected planar maps with a sense-reversing automorphism.
(Formerly M0172)

0, 0, 0, 0, 0, 1, 0, 1, 2, 1, 4, 9, 12, 27, 50, 99, 188, 386, 740, 1528, 3012, 6192, 12376, 25594, 51628, 107135, 218100, 453895, 930812, 1943281, 4009512, 8394915, 17414512

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OFFSET

1,9

COMMENTS

Maps are counted up to isomorphism which is not restricted to those that preserve the orientation of the sphere.

REFERENCES

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

Computed by Nick Wormald (unpublished).

LINKS

Table of n, a(n) for n=1..33.

T. R. S. Walsh, Number of sensed planar maps with n edges and m vertices

CROSSREFS

Sequence in context: A372327 A163547 A015943 * A174255 A254199 A343398

Adjacent sequences: A006442 A006443 A006444 * A006446 A006447 A006448

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, T. R. S. Walsh, personal communication

STATUS

approved