%I #34 Dec 13 2019 05:24:51

%S 1,9,27,135,513,2241,9099,38367,158625,662553,2752731,11468439,

%T 47711457,198638865,826680843,3441111471,14322350529,59614704297,

%U 248130563355,1032793465383,4298762000961,17892665190369,74474188389387,309982363492095,1290232422488673,5370306116406201

%N G.f.: (1 + 7*x) / (1 - 2*x - 9*x^2).

%H Colin Barker, <a href="/A328604/b328604.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 (2,9).

%F a(n) = 2*a(n-1) + 9*a(n-2) for n>1. - _Colin Barker_, Oct 21 2019

%F a(n)/a(n-1) ~ 1 + sqrt(10).

%o (PARI) Vec((1 + 7*x) / (1 - 2*x - 9*x^2) + O(x^30)) \\ _Colin Barker_, Dec 13 2019

%K nonn,easy

%O 0,2

%A _Kyle MacLean Smith_, Oct 20 2019

%E Edited by _N. J. A. Sloane_, Dec 05 2019