%I #9 Mar 13 2021 08:06:07
%S 1,-3,4,-4,6,-12,20,-28,40,-64,104,-160,240,-368,576,-896,1376,-2112,
%T 3264,-5056,7808,-12032,18560,-28672,44288,-68352,105472,-162816,
%U 251392,-388096,599040,-924672,1427456,-2203648,3401728,-5251072,8105984,-12513280,19316736,-29818880,46030848
%N Expansion of (1-x)/(1+2*x+2*x^2+2*x^3).
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (-2,-2,-2).
%F a(0) = 1, a(1) = -3, a(2) = 4, a(n) = -2*(a(n-1) + a(n-2) + a(n-3)) for n > 2. - _Jinyuan Wang_, Apr 07 2020
%o (PARI) Vec((1-x)/(1+2*x+2*x^2+2*x^3) + O(x^50)) \\ _Jinyuan Wang_, Apr 07 2020
%Y First differences of A077993.
%K sign,easy
%O 0,2
%A _N. J. A. Sloane_, Nov 17 2002