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A117374
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Expansion of (1-3x)/(1-x^2+x^3).
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3
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1, -3, 1, -4, 4, -5, 8, -9, 13, -17, 22, -30, 39, -52, 69, -91, 121, -160, 212, -281, 372, -493, 653, -865, 1146, -1518, 2011, -2664, 3529, -4675, 6193, -8204, 10868, -14397, 19072, -25265, 33469
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OFFSET
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0,2
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COMMENTS
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Diagonal sums of number triangle A117372.
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LINKS
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FORMULA
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a(n)=a(n-2)+a(n-3); a(n)=sum{k=0..floor(n/2), (-1)^n*(C(k,n-2k)+3*C(k, n-2k-1))}.
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MATHEMATICA
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CoefficientList[Series[(1-3x)/(1-x^2+x^3), {x, 0, 40}], x] (* or *) LinearRecurrence[{0, 1, -1}, {1, -3, 1}, 40] (* Harvey P. Dale, May 06 2022 *)
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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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