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A077971
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Expansion of 1/(1+x-x^2-2*x^3).
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4
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1, -1, 2, -1, 1, 2, -3, 7, -6, 7, 1, -6, 21, -25, 34, -17, 1, 50, -83, 135, -118, 87, 65, -214, 453, -537, 562, -193, -319, 1250, -1955, 2567, -2022, 679, 2433, -5798, 9589, -10521, 8514, 143, -12671, 29842, -42227, 46727, -29270, -8457, 72641, -139638, 195365, -189721, 105810, 95199, -368831
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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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LinearRecurrence[{-1, 1, 2}, {1, -1, 2}, 60] (* or *) CoefficientList[Series[ 1/(1 +x-x^2-2*x^3), {x, 0, 60}], x] (* G. C. Greubel, Jun 24 2019 *)
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PROG
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(Magma) R<x>:=PowerSeriesRing(Integers(), 60); Coefficients(R!( 1/(1+x-x^2-2*x^3) )); // G. C. Greubel, Jun 24 2019
(Sage) (1/(1+x-x^2-2*x^3)).series(x, 60).coefficients(x, sparse=False) # G. C. Greubel, Jun 24 2019
(GAP) a:=[1, -1, 2];; for n in [4..60] do a[n]:=-a[n-1]+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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