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A217720
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Number of one-sided polydrafters with n cells.
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3
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2, 8, 28, 116, 474, 2001, 8508, 37162, 163730, 729683, 3269602, 14773831
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OFFSET
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1,1
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COMMENTS
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A polydrafter is a plane figure formed by joining equal triangles with angles of 30, 60, and 90 degrees with certain restrictions on how they are joined. See A056842 for details. One-sided means that distinct mirror images are counted separately.
For odd n, an n-drafter cannot have mirror symmetry, so odd entries in this sequence are double those in A056842.
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REFERENCES
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Ed Pegg, Jr., Polyform puzzles, in Tribute to a Mathemagician, Peters, 2005, pp. 119-125.
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LINKS
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EXAMPLE
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There are 6 two-sided didrafters, two have distinct mirror images, so there are 8 one-sided didrafters. Thus a(2) = 8.
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CROSSREFS
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Cf. A056842 (number of two-sided polydrafters).
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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