

A003104


Number of hexagonal nelement polyominoes whose graph is a path.
(Formerly M1208)


10



1, 1, 2, 4, 10, 24, 67, 182, 520, 1474, 4248, 12196, 35168, 101226, 291565, 838764, 2412033, 6929754, 19896915
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OFFSET

1,3


COMMENTS

In other words, number of 2sided strip polyhexes with n cells.


REFERENCES

E. M. Palmer, Variations of the cell growth problem, Lect. Notes Math. 303 (1972), 215224.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

Table of n, a(n) for n=1..19.
A. T. Balaban, J. Brunvoll, B. N. Cyvin & S. J. Cyvin, Enumeration of branched catacondensed benzenoid hydrocarbons and their numbers of KekulĂ© structures Tetrahedron, 44(1) (1988), 221228. See Table 1.
Wenchen He and Wenjie He, Generation and enumeration of planar polycyclic aromatic hydrocarbons, Tetrahedron 42.19 (1986): 52915299. See Table 1, column B.
Ed Pegg, Jr., Illustrations of polyforms
Eric Weisstein's World of Mathematics, Polyhex


CROSSREFS

Sequence in context: A000084 A057734 A151516 * A121186 A028506 A148088
Adjacent sequences: A003101 A003102 A003103 * A003105 A003106 A003107


KEYWORD

nonn,more,changed


AUTHOR

N. J. A. Sloane.


EXTENSIONS

a(8)a(12) from Ed Pegg Jr, May 13 2009
a(13)a(19) from Joseph Myers, Nov 26 2010


STATUS

approved



