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List of triples 2n, 1-2n, 0, n >= 1.
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%I #9 Feb 03 2021 22:21:16

%S 2,-1,0,4,-3,0,6,-5,0,8,-7,0,10,-9,0,12,-11,0,14,-13,0,16,-15,0,18,

%T -17,0,20,-19,0,22,-21,0,24,-23,0,26,-25,0,28,-27,0,30,-29,0,32,-31,0,

%U 34,-33,0,36,-35,0,38,-37,0,40,-39,0,42,-41,0,44,-43,0,46,-45,0,48,-47,0,50,-49,0

%N List of triples 2n, 1-2n, 0, n >= 1.

%H <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (-1,-1,1,1,1).

%F a(n) = sin(n*Pi/3)*((8n+6)*sin(n*Pi/3)-5*sqrt(3)*cos(n*Pi))*(-1)^floor(2n/3)/9. - _Wesley Ivan Hurt_, Sep 24 2017

%F From _Chai Wah Wu_, Feb 03 2021: (Start)

%F a(n) = - a(n-1) - a(n-2) + a(n-3) + a(n-4) + a(n-5) for n > 5.

%F G.f.: x*(-x^3 - x^2 - x - 2)/((x - 1)*(x^2 + x + 1)^2). (End)

%K sign,easy

%O 1,1

%A _Paul Curtz_, Sep 14 2007