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A197552 Number of free poly-IH19-tiles (holes allowed) with n cells. 5
1, 1, 4, 10, 36, 146, 631, 2815, 12987, 60601, 286376, 1364399, 6546220, 31585133 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Equivalently, polyhexes where two polyhexes are considered equivalent if and only if they are related by a translation, a rotation of order 3 or a reflection or glide reflection in a line parallel to the sides of the hexagons.

REFERENCES

Branko Gr├╝nbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Sections 6.2 and 9.4.

LINKS

Table of n, a(n) for n=1..14.

CROSSREFS

Cf. A000228, A001207, A006535, A057973, A197549, A197550, A197551, A197553, A197554.

Sequence in context: A149184 A149185 A149186 * A052572 A079725 A154152

Adjacent sequences:  A197549 A197550 A197551 * A197553 A197554 A197555

KEYWORD

hard,nonn

AUTHOR

Joseph Myers, Oct 16 2011

STATUS

approved

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Last modified March 24 01:20 EDT 2019. Contains 321444 sequences. (Running on oeis4.)