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A006389 Number of planar maps without faces of degree 1.
(Formerly M1632)
0
1, 2, 6, 18, 68, 313, 1592 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

REFERENCES

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

Walsh, T. R. S.; Generating nonisomorphic maps without storing them. SIAM J. Algebraic Discrete Methods 4 (1983), no. 2, 161-178.

CROSSREFS

Sequence in context: A150080 A150081 A006674 * A030269 A150082 A177470

Adjacent sequences:  A006386 A006387 A006388 * A006390 A006391 A006392

KEYWORD

nonn

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

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Last modified February 14 09:42 EST 2012. Contains 205614 sequences.