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%I #12 Sep 08 2022 08:45:08
%S 1,-2,2,2,-12,24,-20,-32,152,-280,192,480,-1904,3232,-1696,-6880,
%T 23616,-36864,12736,95488,-290176,414848,-58368,-1293312,3533056,
%U -4596224,-460288,17179136,-42630144,49981440,19655680,-224534528,509720576,-531060736,-406388736,2894340096,-6038024192
%N Expansion of 1/(1+2*x+2*x^2-2*x^3).
%H G. C. Greubel, <a href="/A077991/b077991.txt">Table of n, a(n) for n = 0..1000</a>
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (-2,-2,2).
%F a(n) = (-1)^n * A077945(n). - _G. C. Greubel_, Jun 26 2019
%t LinearRecurrence[{-2,-2,2}, {1,-2,2}, 40] (* or *) CoefficientList[ Series[1/(1+2*x+2*x^2-2*x^3), {x,40,40}], x] (* _G. C. Greubel_, Jun 26 2019 *)
%o (PARI) Vec(1/(1+2*x+2*x^2-2*x^3)+O(x^40)) \\ _Charles R Greathouse IV_, Sep 27 2012
%o (Magma) R<x>:=PowerSeriesRing(Integers(), 40); Coefficients(R!( 1/(1+2*x+2*x^2-2*x^3) )); // _G. C. Greubel_, Jun 26 2019
%o (Sage) (1/(1+2*x+2*x^2-2*x^3)).series(x, 40).coefficients(x, sparse=False) # _G. C. Greubel_, Jun 26 2019
%o (GAP) a:=[1,-2,2];; for n in [4..40] do a[n]:=-2*(a[n-1]+a[n-2]-a[n-3]); od; a; # _G. C. Greubel_, Jun 26 2019
%Y Cf. A077945.
%K sign,easy
%O 0,2
%A _N. J. A. Sloane_, Nov 17 2002
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