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A130507 First differences of A130845.

%I A130507 #12 Sep 25 2017 11:25:12
%S A130507 0,0,1,0,0,0,2,-1,0,0,3,-2,0,0,4,-3,0,0,5,-4,0,0,6,-5,0,0,7,-6,0,0,8,
%T A130507 -7,0,0,9,-8,0,0,10,-9,0,0,11,-10,0,0,12,-11,0,0,13,-12,0,0,14,-13,0,
%U A130507 0,15,-14,0,0,16,-15,0,0,17,-16,0,0,18,-17,0,0,19,-18,0,0,20,-19,0,0,21,-20,0,0,22,-21,0,0,23,-22,0,0,24,-23,0,0,25,-24,0
%N A130507 First differences of A130845.
%H A130507 Colin Barker, <a href="/A130507/b130507.txt">Table of n, a(n) for n = 0..1000</a>
%H A130507 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (-1,-1,-1,1,1,1,1).
%F A130507 a(n) = (1/16)*(cos(n*Pi/2)+sin(n*Pi/2)-1)*((2n-1)*cos(n*Pi/2)-5*cos(n*Pi)+(2n-1)*sin(n*Pi/2))*(-1)^floor((n-1)/2). - _Wesley Ivan Hurt_, Sep 24 2017
%F A130507 From _Colin Barker_, Sep 25 2017: (Start)
%F A130507 G.f.: x^2*(1 + x + x^2 + x^3 + x^4) / ((1 - x)*(1 + x)^2*(1 + x^2)^2).
%F A130507 a(n) = -a(n-1) - a(n-2) - a(n-3) + a(n-4) + a(n-5) + a(n-6) + a(n-7) for n>6.
%F A130507 (End)
%o A130507 (PARI) concat(vector(2), Vec(x^2*(1 + x + x^2 + x^3 + x^4) / ((1 - x)*(1 + x)^2*(1 + x^2)^2) + O(x^100))) \\ _Colin Barker_, Sep 25 2017
%Y A130507 Cf. A130845.
%K A130507 sign,easy
%O A130507 0,7
%A A130507 _Paul Curtz_, Aug 16 2007
%E A130507 One term corrected by _Colin Barker_, Sep 25 2017