%I #30 Dec 12 2023 08:54:47

%S 0,0,1,1,0,0,-1,-1,0,0,1,1,0,0,-1,-1,0,0,1,1,0,0,-1,-1,0,0,1,1,0,0,-1,

%T -1,0,0,1,1,0,0,-1,-1,0,0,1,1,0,0,-1,-1,0,0,1,1,0,0,-1,-1,0,0,1,1,0,0,

%U -1,-1,0,0,1,1,0,0,-1,-1,0,0,1,1,0,0,-1,-1,0,0,1,1,0,0,-1,-1

%N Period 8: repeat [0, 0, 1, 1, 0, 0, -1, -1].

%H Antti Karttunen, <a href="/A132380/b132380.txt">Table of n, a(n) for n = 0..8191</a>

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,-1).

%F O.g.f.: x^2*(1+x)/(1+x^4). - _R. J. Mathar_, Apr 06 2008

%F For n > 0, a(n) = A109247(n)/-3. - _Antti Karttunen_, Aug 12 2017

%F a(n) = (1/2)*(1-(-1)^floor(n/2))*(-1)^floor(n/4). - _Wesley Ivan Hurt_, Aug 31 2019

%t PadRight[{},120,{0,0,1,1,0,0,-1,-1}] (* _Harvey P. Dale_, Mar 17 2016 *)

%o (PARI) a(n)=[0,0,1,1,0,0,-1,-1][n%8+1] \\ _Charles R Greathouse IV_, Jun 02 2011

%o (Scheme) (define (A132380 n) (list-ref '(0 0 1 1 0 0 -1 -1) (modulo n 8))) ;; _Antti Karttunen_, Aug 12 2017

%Y Cf. A109247.

%K sign,easy,less

%O 0,1

%A _Paul Curtz_, Nov 10 2007