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 A117080 a(n) = 2a(n-1)+a(n-3)+1 with a(1)=1, a(2)=3, a(3)=8. 0

%I

%S 1,3,8,18,40,89,197,435,960,2118,4672,10305,22729,50131,110568,243866,

%T 537864,1186297,2616461,5770787,12727872,28072206,61915200,136558273,

%U 301188753,664292707,1465143688,3231476130,7127244968,15719633625,34670743381,76468731731

%N a(n) = 2a(n-1)+a(n-3)+1 with a(1)=1, a(2)=3, a(3)=8.

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (3, -2, 1, -1).

%F a(n)=3*a(n-1)-2*a(n-2)+a(n-3)-a(n-4). G.f.: x*(-1-x^2+x^3)/((1-x)*(x^3+2*x-1)). [From _R. J. Mathar_, May 25 2009]

%K nonn

%O 1,2

%A _N. J. A. Sloane_, following a suggestion of Franklin T. Adams-Watters, Apr 20 2006

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Last modified May 10 15:00 EDT 2021. Contains 343773 sequences. (Running on oeis4.)