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A133513
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Period 6: repeat [0, 1, -3, 0, -1, 3].
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2
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0, 1, -3, 0, -1, 3, 0, 1, -3, 0, -1, 3, 0, 1, -3, 0, -1, 3, 0, 1, -3, 0, -1, 3, 0, 1, -3, 0, -1, 3, 0, 1, -3, 0, -1, 3, 0, 1, -3, 0, -1, 3, 0, 1, -3, 0, -1, 3, 0, 1, -3, 0, -1, 3, 0, 1, -3, 0, -1, 3, 0, 1, -3, 0, -1, 3, 0, 1, -3, 0, -1, 3, 0, 1, -3, 0, -1, 3
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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*(1-3*x)/(1+x^3).
a(n) + a(n-3) = 0 for n>2.
a(n) = 2 * sin(n*Pi/3) * (4*sin(2*n*Pi/3) - sqrt(3))/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,less
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AUTHOR
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STATUS
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approved
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