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(11*9^n+1)/4.
1

%I #12 Sep 08 2022 08:46:00

%S 3,25,223,2005,18043,162385,1461463,13153165,118378483,1065406345,

%T 9588657103,86297913925,776681225323,6990131027905,62911179251143,

%U 566200613260285,5095805519342563,45862249674083065,412760247066747583

%N (11*9^n+1)/4.

%H Vincenzo Librandi, <a href="/A199679/b199679.txt">Table of n, a(n) for n = 0..1000</a>

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

%F a(n) = 9*a(n-1)-2.

%F a(n) = 10*a(n-1)-9*a(n-2).

%F G.f.: (3-5*x)/((1-x)*(1-9*x)).

%t (11 9^Range[0,20]+1)/4 (* or *) LinearRecurrence[{10,-9},{3,25},20] (* _Harvey P. Dale_, Apr 29 2019 *)

%o (Magma) [(11*9^n+1)/4: n in [0..30]];

%K nonn,easy

%O 0,1

%A _Vincenzo Librandi_, Nov 09 2011