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%I #16 Jul 16 2017 05:48:22
%S 1,5,35,287,2501,22265,199655,1794707,16145801,145292525,1307573675,
%T 11767985927,105911341901,953200482785,8578799562095,77209181709947,
%U 694882592342801,6253943201945045,56285488430084915,506569394708502767,4559124548889740501
%N a(n) = (3^n+1) * (3^(n+1)+1) / 8.
%H Colin Barker, <a href="/A051406/b051406.txt">Table of n, a(n) for n = 0..1000</a>
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (13,-39,27).
%F a(n) = 13*a(n-1) - 39*a(n-2) + 27*a(n-3). G.f.: -(1-8*x+9*x^2)/((x-1)*(3*x-1)*(9*x-1)). [_R. J. Mathar_, Jul 25 2009]
%o (PARI) Vec((1 - 8*x + 9*x^2) / ((1 - x)*(1 - 3*x)*(1 - 9*x)) + O(x^30)) \\ _Colin Barker_, Jul 16 2017
%K nonn,easy
%O 0,2
%A _Colin Mallows_
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