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%I #15 Apr 07 2020 03:36:51
%S 1,-2,4,-10,22,-50,114,-258,586,-1330,3018,-6850,15546,-35282,80074,
%T -181730,412442,-936050,2124394,-4821378,10942266,-24833810,56361098,
%U -127913250,290303066,-658851762,1495284394,-3393594050,7701866362,-17479623250,39670544074,-90033523298
%N Expansion of (1-x)/(1+x-2*x^2+2*x^3).
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (-1,2,-2).
%F a(0) = 1, a(1) = -2, a(2) = 4, a(n) = -a(n-1) + 2*a(n-2) - 2*a(n-3) for n > 2. - _Harvey P. Dale_, Dec 09 2011
%t CoefficientList[Series[(1-x)/(1+x-2x^2+2x^3),{x,0,40}],x] (* or *) LinearRecurrence[{-1,2,-2},{1,-2,4},40] (* _Harvey P. Dale_, Dec 09 2011 *)
%o (PARI) Vec((1-x)/(1+x-2*x^2+2*x^3)+O(x^99)) \\ _Charles R Greathouse IV_, Sep 27 2012
%Y First differences of A077970.
%K sign,easy
%O 0,2
%A _N. J. A. Sloane_, Nov 17 2002
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