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A151525 Number of poly-IH64-tiles (holes allowed) with n cells. 3
1, 2, 4, 12, 35, 116, 392, 1390, 4998, 18321, 67791, 253288, 952527, 3603761, 13699516, 52301427, 200406183, 770429000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Equivalently, polyominoes where two polyominoes are considered the same if and only if they are related by a translation or a reflection in a horizontal line.  Formerly described as one-sided polyrects, but that is A151522.

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..18.

CROSSREFS

Polyominoes by group of symmetries relating shapes considered the same: A000105 (all symmetries), A001168 (translations only), A000988 (rotations and translations), A056780 (horizontal and vertical reflections, rotations of order 2 and translations), A056783 (reflections in either diagonal, rotations of order 2 and translations), A151522 (rotations of order 2 and translations), A151525 (reflections in a horizontal line and translations), A182645 (reflections in a NE-SW diagonal line and translations)

Sequence in context: A209027 A069727 A148204 * A148205 A019447 A148206

Adjacent sequences:  A151522 A151523 A151524 * A151526 A151527 A151528

KEYWORD

nonn

AUTHOR

Ed Pegg Jr, May 13 2009

EXTENSIONS

Edited and a(13)-a(18) by Joseph Myers, Nov 24 2010

STATUS

approved

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Last modified May 27 22:57 EDT 2017. Contains 287210 sequences.