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A131193
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Period 6: repeat [0, 1, -3, 3, -1, 0].
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2
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0, 1, -3, 3, -1, 0, 0, 1, -3, 3, -1, 0, 0, 1, -3, 3, -1, 0, 0, 1, -3, 3, -1, 0, 0, 1, -3, 3, -1, 0, 0, 1, -3, 3, -1, 0, 0, 1, -3, 3, -1, 0, 0, 1, -3, 3, -1, 0, 0, 1, -3, 3, -1, 0, 0, 1, -3, 3, -1, 0, 0, 1, -3, 3, -1, 0, 0, 1, -3, 3, -1, 0, 0, 1, -3, 3, -1, 0, 0, 1, -3, 3, -1, 0
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OFFSET
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0,3
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LINKS
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FORMULA
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G.f.: x*(x-1)^2/((x+1)*(x^2-x+1)*(x^2+x+1)). - R. J. Mathar, Nov 14 2007
a(n) + a(n-1) + a(n-2) + a(n-3) + a(n-4) + a(n-5) = 0 for n>4.
a(n) = sin(n*Pi/6) * (2*sqrt(3)*cos(n*Pi/6) + 3*sqrt(3)*cos(n*Pi/2) - sin(n*Pi/2) + 8*sin(5*n*Pi/6))/3. (End)
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MAPLE
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MATHEMATICA
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PROG
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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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