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A217745
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Number of regions in the exterior of a regular n-gon with all diagonals drawn.
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3
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1, 4, 10, 18, 35, 64, 117, 190, 330, 492, 780, 1050, 1605, 2080, 2941
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OFFSET
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3,2
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LINKS
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EXAMPLE
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a(3) = 1 since the equilateral triangle has no diagonals and therefore one exterior region (with infinite area).
a(4) = 4 since the two diagonals of the square divide the exterior in four regions (with infinite area).
a(5) = 10 since the ten diagonals of the regular pentagon divide the exterior in ten regions (with infinite area) of two different shapes.
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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