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A112030
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a(n) = (2 + (-1)^n) * (-1)^floor(n/2).
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12
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3, 1, -3, -1, 3, 1, -3, -1, 3, 1, -3, -1, 3, 1, -3, -1, 3, 1, -3, -1, 3, 1, -3, -1, 3, 1, -3, -1, 3, 1, -3, -1, 3, 1, -3, -1, 3, 1, -3, -1, 3, 1, -3, -1, 3, 1, -3, -1, 3, 1, -3, -1, 3, 1, -3, -1, 3, 1, -3, -1, 3, 1, -3, -1, 3, 1, -3, -1, 3, 1, -3, -1, 3, 1, -3, -1, 3, 1
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OFFSET
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0,1
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COMMENTS
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The fractions A112031(n)/A112032(n) give the partial sums of a(n)/floor((n+4)/2).
Sum of the two Cartesian coordinates from the image of the point (2,1) after n 90-degree counterclockwise rotations about the origin. - Wesley Ivan Hurt, Jul 06 2013
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LINKS
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FORMULA
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a(n) = A010684(n+1) * (-1)^floor(n/2).
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MAPLE
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(2 + (-1)^n) * (-1)^floor(n/2) ;
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MATHEMATICA
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PROG
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(Python)
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CROSSREFS
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KEYWORD
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sign,easy
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AUTHOR
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STATUS
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approved
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