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A075211 Number of polyhexes with n cells that tile the plane by 180-degree rotation (Conway criterion). 10
1, 1, 3, 7, 21, 75, 256, 929, 3090, 9235, 21216, 80463, 138623, 423595, 1160355, 2456117, 4272856, 15986299, 21709209, 75452662, 156068738 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

REFERENCES

Branko Gr├╝nbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Section 9.4.

LINKS

Table of n, a(n) for n=1..21.

Joseph Myers, Polyhex tiling

CROSSREFS

Cf. A070766, A075207, A075208, A075209, A075210, A075212, A075213, A075214, A075215, A075202, A075220.

Sequence in context: A148680 A001576 A169587 * A075212 A173794 A049365

Adjacent sequences:  A075208 A075209 A075210 * A075212 A075213 A075214

KEYWORD

hard,nonn

AUTHOR

Joseph Myers, Sep 08 2002

EXTENSIONS

More terms from Joseph Myers, Nov 08 2003

a(20) and a(21) from Joseph Myers, Nov 21 2010

STATUS

approved

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Last modified March 27 04:08 EDT 2017. Contains 284144 sequences.