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A131360 a(4n) = a(4n+1) = 0, a(4n+2) = 2n, a(4n+3) = 2n+1.

%I A131360 #22 Oct 29 2021 15:19:25
%S A131360 0,0,0,1,0,0,2,3,0,0,4,5,0,0,6,7,0,0,8,9,0,0,10,11,0,0,12,13,0,0,14,
%T A131360 15,0,0,16,17,0,0,18,19,0,0,20,21,0,0,22,23,0,0,24,25,0,0,26,27,0,0,
%U A131360 28,29,0,0,30,31,0,0,32,33,0,0,34,35,0,0,36,37,0,0,38,39,0,0,40,41,0,0,42,43
%N A131360 a(4n) = a(4n+1) = 0, a(4n+2) = 2n, a(4n+3) = 2n+1.
%H A131360 Colin Barker, <a href="/A131360/b131360.txt">Table of n, a(n) for n = 0..1000</a>
%H A131360 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (1,-1,1,1,-1,1,-1).
%F A131360 G.f.: x^3*(x^3+x^2-x+1) / ((x-1)^2*(x+1)*(x^2+1)^2). - _Colin Barker_, Jul 01 2015
%F A131360 a(n) = (cos(n*Pi/2)+sin(n*Pi/2)-1)*((2n-3)*cos(n*Pi/2)+cos(n*Pi)+(2n-3)*sin(n*Pi/2))/8. - _Wesley Ivan Hurt_, Sep 24 2017
%F A131360 a(n) = floor((n-1)/2)*A021913(n). - _Lechoslaw Ratajczak_, Sep 22 2021
%t A131360 Array[Floor[(# - 1)/2] Floor[Mod[#, 4]/2] &, 88, 0] (* _Michael De Vlieger_, Sep 22 2021 *)
%o A131360 (PARI) concat(vector(3), Vec(x^3*(x^3+x^2-x+1)/((x-1)^2*(x+1)*(x^2+1)^2) + O(x^100))) \\ _Colin Barker_, Jul 01 2015
%Y A131360 Cf. A142150, A021913.
%K A131360 nonn,easy
%O A131360 0,7
%A A131360 _Paul Curtz_, Sep 30 2007