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A099531
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Expansion of (1+x)^3/((1+x)^3+x^4).
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3
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1, 0, 0, 0, -1, 3, -6, 10, -14, 15, -7, -20, 80, -188, 351, -549, 702, -622, -42, 1839, -5471, 11560, -20064, 29144, -33329, 21059, 27730, -142182, 355626, -689121, 1114937, -1490892, 1461360, -337220, -2996465, 10030587, -22226506, 39921442, -60118930, 72788383, -55703295, -31057776
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OFFSET
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0,6
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COMMENTS
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LINKS
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FORMULA
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a(n)=-3a(n-1)-3a(n-2)-a(n-3)-a(n-4); a(n)=sum{j=0..n, sum{k=0..floor(j/4), C(n, j)(-1)^(n-j)C(j-3k, k)(-1)^k}}.
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MATHEMATICA
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CoefficientList[Series[(1+x)^3/((1+x)^3+x^4), {x, 0, 50}], x] (* or *) LinearRecurrence[{-3, -3, -1, -1}, {1, 0, 0, 0}, 50] (* Harvey P. Dale, Feb 21 2016 *)
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CROSSREFS
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KEYWORD
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easy,sign
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AUTHOR
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STATUS
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approved
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