%I #6 Apr 07 2020 03:37:52
%S 1,-3,7,-19,51,-135,359,-955,2539,-6751,17951,-47731,126915,-337463,
%T 897303,-2385899,6344027,-16868559,44852943,-119262499,317115059,
%U -843198503,2242037063,-5961502747,15851439563,-42148455999,112071357055,-297994049235,792356367523,-2106849498391
%N Expansion of (1-x)/(1+2*x-x^2+2*x^3).
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (-2,1,-2).
%F a(0) = 1, a(1) = -3, a(2) = 7, a(n) = -2*a(n-1) + a(n-2) - 2*a(n-3) for n > 2. - _Jinyuan Wang_, Apr 07 2020
%o (PARI) Vec((1-x)/(1+2*x-x^2+2*x^3) + O(x^50)) \\ _Jinyuan Wang_, Apr 07 2020
%K sign,easy
%O 0,2
%A _N. J. A. Sloane_, Nov 17 2002