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A006389
Number of unsensed planar maps with n edges and without faces of degree 1.
(Formerly M1632)
0
1, 2, 6, 18, 68, 313, 1592, 9187, 57451, 384450, 2703970, 19769311
OFFSET
1,2
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
Timothy R. Walsh, Generating nonisomorphic maps without storing them, SIAM J. Algebraic Discrete Methods 4 (1983), no. 2, 161-178.
CROSSREFS
Cf. A006385.
Sequence in context: A150080 A150081 A006674 * A030269 A150082 A177470
KEYWORD
nonn,more
EXTENSIONS
a(8)-a(12) from Sean A. Irvine, Mar 28 2017
STATUS
approved