This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A132380 #30 Dec 12 2023 08:54:47
%S A132380 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 A132380 -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 A132380 -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 A132380 Period 8: repeat [0, 0, 1, 1, 0, 0, -1, -1].
%H A132380 Antti Karttunen, <a href="/A132380/b132380.txt">Table of n, a(n) for n = 0..8191</a>
%H A132380 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,-1).
%F A132380 O.g.f.: x^2*(1+x)/(1+x^4). - _R. J. Mathar_, Apr 06 2008
%F A132380 For n > 0, a(n) = A109247(n)/-3. - _Antti Karttunen_, Aug 12 2017
%F A132380 a(n) = (1/2)*(1-(-1)^floor(n/2))*(-1)^floor(n/4). - _Wesley Ivan Hurt_, Aug 31 2019
%t A132380 PadRight[{},120,{0,0,1,1,0,0,-1,-1}] (* _Harvey P. Dale_, Mar 17 2016 *)
%o A132380 (PARI) a(n)=[0,0,1,1,0,0,-1,-1][n%8+1] \\ _Charles R Greathouse IV_, Jun 02 2011
%o A132380 (Scheme) (define (A132380 n) (list-ref '(0 0 1 1 0 0 -1 -1) (modulo n 8))) ;; _Antti Karttunen_, Aug 12 2017
%Y A132380 Cf. A109247.
%K A132380 sign,easy,less
%O A132380 0,1
%A A132380 _Paul Curtz_, Nov 10 2007