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A319324
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a(n) is the number of fixed polyglasses (polyiamonds which need only touch at corners) with n cells.
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4
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2, 12, 88, 710, 6054, 53500, 484784, 4475010, 41902626, 396838992, 3793117200, 36534684066
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OFFSET
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1,1
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COMMENTS
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Polyglasses are to polyiamonds (A001420) as polyplets (A006770) are to polyominoes (A001168). The name derives from the 2-celled animal (diglass) which looks like an hourglass.
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LINKS
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EXAMPLE
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a(2) = 12: three rotations of a diamond, three rotations of an hourglass and six rotations of "two mountains".
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CROSSREFS
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KEYWORD
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nonn,more,hard
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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