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A144553
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Number of polyominoes with n cells that have precisely the symmetry group of order 4 generated by 90-degree rotations.
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22
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0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 3, 2, 0, 0, 12, 7, 0, 0, 44, 25, 0, 0, 165, 90, 0, 0, 603
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OFFSET
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1,12
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LINKS
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Table of n, a(n) for n=1..28.
Tomás Oliveira e Silva, Enumeration of polyominoes
D. H. Redelmeier, Counting polyominoes: yet another attack, Discrete Math., 36 (1981), 191-203.
D. H. Redelmeier, Table 3 of Counting polyominoes...
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CROSSREFS
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Sequences classifying polyominoes by symmetry group: A000105, A006746, A006747, A006748, A006749, A056877, A056878, A142886, A144553, A144554.
Sequence in context: A246159 A059033 A133209 * A187130 A187145 A285700
Adjacent sequences: A144550 A144551 A144552 * A144554 A144555 A144556
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KEYWORD
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nonn,more
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AUTHOR
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N. J. A. Sloane, Jan 01 2009
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EXTENSIONS
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a(28) added by Andrew Howroyd, Dec 04 2018
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STATUS
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approved
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