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 A168569 a(n) = 9*(3^n - 1)/2. 2
 0, 9, 36, 117, 360, 1089, 3276, 9837, 29520, 88569, 265716, 797157, 2391480, 7174449, 21523356, 64570077, 193710240, 581130729, 1743392196, 5230176597, 15690529800, 47071589409, 141214768236, 423644304717, 1270932914160 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (4,-3). FORMULA From R. J. Mathar, Jan 04 2011: (Start) a(n) = 9*A003462(n). G.f.: 9*x / ( (3*x-1)*(x-1) ). (End) a(n) = 4*a(n-1)-3*a(n-2). - Robert Israel, Sep 24 2014 E.g.f.: (9/2)*(exp(3*x) - exp(x)). - G. C. Greubel, Jul 26 2016 MATHEMATICA 9 (3^Range[0, 30]-1)/2  (* Harvey P. Dale, Mar 18 2011 *) CoefficientList[Series[9 x / ((1 - x) (1 - 3 x)), {x, 0, 30}], x] (* Vincenzo Librandi, Sep 24 2014 *) PROG (MAGMA) [9*(3^n-1)/2: n in [0..30]]; // Vincenzo Librandi, Sep 24 2014 (PARI) a(n)=9*(3^n-1)/2 \\ Charles R Greathouse IV, Jul 26 2016 CROSSREFS Cf. A003462. Sequence in context: A212104 A193007 A259279 * A213283 A188162 A023872 Adjacent sequences:  A168566 A168567 A168568 * A168570 A168571 A168572 KEYWORD nonn,easy AUTHOR Vincenzo Librandi, Nov 30 2009 STATUS approved

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Last modified May 29 15:44 EDT 2020. Contains 334704 sequences. (Running on oeis4.)