%I #18 Dec 12 2023 09:00:36

%S 2,-3,4,-3,2,-3,4,-3,2,-3,4,-3,2,-3,4,-3,2,-3,4,-3,2,-3,4,-3,2,-3,4,

%T -3,2,-3,4,-3,2,-3,4,-3,2,-3,4,-3,2,-3,4,-3,2,-3,4,-3,2,-3,4,-3,2,-3,

%U 4,-3,2,-3,4,-3,2,-3,4,-3,2,-3,4,-3,2,-3,4,-3,2,-3,4,-3,2,-3,4,-3,2,-3,4,-3,2,-3,4,-3,2,-3,4,-3

%N Period 4: repeat [2, -3, 4, -3].

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (-1,-1,-1).

%F From _Luce ETIENNE_, Mar 25 2017: (Start)

%F a(n)= (6*(-1)^n-(-1)^((2*n+1-(-1)^n)/4)-(-1)^((2*n-1+(-1)^n)/4))/2.

%F a(n) = 3*cos(n*Pi)-cos(n*Pi/2). (End)

%K sign,easy

%O 0,1

%A _Paul Curtz_, Sep 17 2007

%E Better name from _Joerg Arndt_, Apr 02 2017