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a(n) = 3^(2*n-1) + 2.
4

%I #19 Jan 04 2021 13:56:03

%S 5,29,245,2189,19685,177149,1594325,14348909,129140165,1162261469,

%T 10460353205,94143178829,847288609445,7625597484989,68630377364885,

%U 617673396283949,5559060566555525,50031545098999709,450283905890997365,4052555153018976269

%N a(n) = 3^(2*n-1) + 2.

%C Suggested by a posting from _Luis H. Gallardo_ to the Number Theory List, Jan 14 2008

%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (10,-9).

%F a(1)=5, a(2)=29, a(n)=10*a(n-1)-9*a(n-2). - _Harvey P. Dale_, Dec 08 2015

%t 3^(2*Range[20]-1)+2 (* or *) LinearRecurrence[{10, -9}, {5, 29}, 20] (* _Harvey P. Dale_, Dec 08 2015 *)

%Y Cf. A134753.

%K nonn,easy

%O 1,1

%A _N. J. A. Sloane_, Jan 28 2008