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A006400
Number of connected planar maps without vertices of degree 1.
(Formerly M1404)
0
1, 1, 2, 5, 11, 33, 117, 431, 1755, 7485
OFFSET
3,3
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
Sequence in context: A056365 A276548 A353016 * A254342 A080068 A226919
KEYWORD
nonn,more
EXTENSIONS
a(11) and a(12) from Sean A. Irvine, Mar 30 2017
STATUS
approved