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A077970
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Expansion of 1/(1+x-2*x^2+2*x^3).
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4
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1, -1, 3, -7, 15, -35, 79, -179, 407, -923, 2095, -4755, 10791, -24491, 55583, -126147, 286295, -649755, 1474639, -3346739, 7595527, -17238283, 39122815, -88790435, 201512631, -457339131, 1037945263, -2355648787, 5346217575, -12133405675, 27537138399, -62496384899, 141837473047
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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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MATHEMATICA
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CoefficientList[Series[1/(1+x-2x^2+2x^3), {x, 0, 40}], x] (* or *) LinearRecurrence[ {-1, 2, -2}, {1, -1, 3}, 40] (* Harvey P. Dale, Sep 29 2018 *)
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PROG
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(Magma) R<x>:=PowerSeriesRing(Integers(), 40); Coefficients(R!( 1/(1+x-2*x^2+2*x^3) )); // G. C. Greubel, Jun 24 2019
(Sage) (1/(1+x-2*x^2+2*x^3)).series(x, 40).coefficients(x, sparse=False) # G. C. Greubel, Jun 24 2019
(GAP) a:=[1, 1, -3];; for n in [4..40] do a[n]:=-a[n-1]+2*a[n-2]-2*a[n-3]; od; a; # G. C. Greubel, Jun 24 2019
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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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