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%I #22 Aug 01 2015 09:13:54
%S 36,90,198,414,846,1710,3438,6894,13806,27630,55278,110574,221166,
%T 442350,884718,1769454,3538926,7077870,14155758,28311534,56623086,
%U 113246190,226492398,452984814,905969646,1811939310,3623878638,7247757294,14495514606,28991029230
%N a(n) = 3a(n-1) - 2a(n-2) with a(0)=36 and a(1)=90.
%C Number of vertices into building blocks of 3d objects with 9 vertices.
%H Vincenzo Librandi, <a href="/A182467/b182467.txt">Table of n, a(n) for n = 0..1000</a>
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (3, -2).
%F a(n) = a(n-1)*2 + 18
%F G.f.: -((18*(x-2))/(2*x^2-3*x+1)). - _Harvey P. Dale_, Apr 29 2013
%F a(n) = 18*A153893(n). - _Michel Marcus_, Jun 01 2014
%e a(0) = 9+18+9;
%e a(1) = 9+18+36+18+9;
%e a(2) = 9+18+36+72+36+18+9;
%e a(3) = 9+18+36+72+144+72+36+18+9.
%t LinearRecurrence[{3,-2},{36,90},30] (* or *) CoefficientList[Series[(-18(x-2))/(1-3x+2x^2),{x,0,30}],x] (* _Harvey P. Dale_, Apr 29 2013 *)
%Y Cf. A000045, A028399, A038578, A089143, A173033, A182461, A182462, A182464, A182465, A182466.
%K nonn,easy
%O 0,1
%A _Odimar Fabeny_, Apr 30 2012
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