

A151525


Number of polyIH64tiles (holes allowed) with n cells.


4



1, 2, 4, 12, 35, 116, 392, 1390, 4998, 18321, 67791, 253288, 952527, 3603761, 13699516, 52301427, 200406183, 770429000, 2970400815, 11482461055, 44491876993, 172766558719, 672186631950, 2619995431640, 10228902801505, 39996342220199, 156612023001490, 614044351536722
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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 onesided polyrects, but that is A151522.


REFERENCES

Branko Grünbaum 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..28.
JeanFrançois Alcover, Mathematica program
Wikipedia, Polyomino


FORMULA

a(n) = 4*A006749(n) + 3*A006746(n) + 2*A006748(n) + 2*A006747(n) + 2*A056877(n) + A056878(n) + A144553(n) + A142886(n).  Andrew Howroyd, Dec 04 2018


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 NESW 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
a(19)a(28) from Andrew Howroyd, Dec 04 2018


STATUS

approved



