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A005500
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Number of unrooted triangulations of a quadrilateral with n internal nodes.
(Formerly M1516)
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20
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1, 2, 5, 18, 88, 489, 3071, 20667, 146381, 1072760, 8071728, 61990477, 484182622, 3835654678, 30757242535, 249255692801, 2038827903834, 16815060576958, 139706974995635, 1168468902294726, 9831504782276593, 83174244225508659, 707159273362126228, 6039827641569969225
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,2
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COMMENTS
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These are also called [n,1]-triangulations.
Graphs can be enumerated and counted using the tool "plantri", in particular the command "./plantri -s -P4 -c2m2 [n]". - Manfred Scheucher, Mar 08 2018
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REFERENCES
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C. F. Earl and L. J. March, Architectural applications of graph theory, pp. 327-355 of R. J. Wilson and L. W. Beineke, editors, Applications of Graph Theory. Academic Press, NY, 1979.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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FORMULA
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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Name clarified and terms a(13) and beyond from Andrew Howroyd, Feb 22 2021
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STATUS
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approved
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