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%I #9 Jun 13 2015 00:49:48
%S 0,2,24,350,4896,68962,970200,13652158,192099456,2703046850,
%T 38034749784,535189557278,7530688519200,105964828904482,
%U 1491038292992664,20980500931258750,295218051329511936,4154033219547089282,58451683124982331800,822477596969315258078
%N a(n)= A000129(n)*A000129(2*n) where A000129(n) are the Pell numbers.
%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (12,30,-12,-1).
%F a(n) is asymptotic to (1/8)*(7+2*sqrt(5))^n.
%F a(n) = 2 * A052208(n).
%F G.f.: 2*x*(x^2+1) / ((x^2-2*x-1)*(x^2+14*x-1)). - _Colin Barker_, Oct 19 2013
%o (PARI) a(n)=if(n<0,0,contfracpnqn(vector(n,i,1+(i>1)))[2,1]*contfracpnqn(vector (2*n,i,1+(i>1)))[2,1])
%o (PARI) Vec(2*x*(x^2+1)/((x^2-2*x-1)*(x^2+14*x-1)) + O(x^100)) \\ _Colin Barker_, Oct 19 2013
%Y Cf. A000129.
%K nonn,easy
%O 0,2
%A _Gary W. Adamson_, Feb 01 2000
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