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 A169725 3^(n-1)*(6*3^(n-1)+5)+1. 1
 12, 70, 532, 4510, 39772, 355510, 3192292, 28708750, 258313132, 2324621350, 20921001652, 188287243390, 1694579876092, 15251202941590, 137260778644612, 1235346864312430, 11118121348344652, 100063090843700230, 900567813719097172, 8105110311849259870 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 Alice V. Kleeva, Grid for this sequence Alice V. Kleeva, Illustration of initial terms Robert Munafo, Sequence A169720, and two others by Alice V. Kleeva Robert Munafo, Sequence A169720, and two others by Alice V. Kleeva [Cached copy, in pdf format, included with permission] Index entries for linear recurrences with constant coefficients, signature (13,-39,27). FORMULA a(n)= +13*a(n-1) -39*a(n-2) +27*a(n-3). G.f.: x*( -12+86*x-90*x^2 ) / ( (x-1)*(3*x-1)*(9*x-1) ). [R. J. Mathar, Apr 26 2010] MAPLE A169725 := proc(n)     3^(n-1)*(6*3^(n-1)+5)+1 ; end proc: # R. J. Mathar, Jun 02 2016 MATHEMATICA Table[3^(n-1) (6 3^(n - 1) + 5) + 1, {n, 20}] (* or *) LinearRecurrence[{13, -39, 27}, {12, 70, 532}, 20] (* Harvey P. Dale, Aug 10 2011 *) CoefficientList[Series[(-12 + 86 x - 90 x^2)/((x - 1) (3 x - 1) (9 x - 1)), {x, 0, 30}], x] (* Vincenzo Librandi, Dec 03 2012 *) PROG (MAGMA) I:=[12, 70, 532]; [n le 3 select I[n] else 13*Self(n-1) -39*Self(n-2) +27*Self(n-3): n in [1..30]]; // Vincenzo Librandi, Dec 03 2012 CROSSREFS Cf. A169720-A169727, A100702. Sequence in context: A088832 A198311 A060930 * A209447 A219302 A338261 Adjacent sequences:  A169722 A169723 A169724 * A169726 A169727 A169728 KEYWORD nonn,easy AUTHOR Alice V. Kleeva (alice27353(AT)gmail.com), Jan 19 2010 EXTENSIONS G.f. adapted to the offset by Vincenzo Librandi, Dec 03 2012 STATUS approved

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Last modified November 29 04:08 EST 2021. Contains 349416 sequences. (Running on oeis4.)