%I #27 Dec 14 2023 06:06:36
%S 2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,
%T 2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,2,9,
%U 2,9,2,9,2,9,2,9,2,9,2,9,2
%N Period 2: repeat (2,9).
%C Continued fraction of 1 + sqrt(11)/3 = A176056. - _R. J. Mathar_, Nov 21 2011
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0,1).
%F a(n) = -7/2*(-1)^n+11/2. - _Paolo P. Lava_, Oct 20 2006
%F G.f.: (2+9x)/((1-x)(1+x)). - _R. J. Mathar_, Nov 21 2011
%F a(n) = 2 + 7*(n mod 2) = 2 + 7*A000035(n). - _M. F. Hasler_, Feb 26 2020
%t PadRight[{},100,{2,9}] (* _Harvey P. Dale_, Mar 25 2015 *)
%o (PARI) a(n)=n%2*7+2 \\ _Charles R Greathouse IV_, Jul 13 2016
%Y Equals 2 + A010678 = 2 + 7*A000035.
%K nonn,easy
%O 0,1
%A _N. J. A. Sloane_
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