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A003104
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Number of hexagonal n-element polyominoes whose graph is a path.
(Formerly M1208)
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11
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1, 1, 2, 4, 10, 24, 67, 182, 520, 1474, 4248, 12196, 35168, 101226, 291565, 838764, 2412033, 6929754, 19896915, 57084939
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,3
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COMMENTS
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In other words, number of 2-sided strip polyhexes with n cells.
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REFERENCES
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E. M. Palmer, Variations of the cell growth problem, Lect. Notes Math. 303 (1972), 215-224.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
N. Trinajstić, S. Nikolić, J. V. Knop, W. R. Müller and K. Szymanski, Computational Chemical Graph Theory: Characterization, Enumeration, and Generation of Chemical Structures by Computer Methods, Ellis Horwood, 1991.
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LINKS
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Eric Weisstein's World of Mathematics, Polyhex
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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a(20) from Trinajstić et al. (Table 4.2, the number of cata-condensed benzenoids with h hexagons, unbranched) added by Andrey Zabolotskiy, Feb 08 2023
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STATUS
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approved
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