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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 A101523

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 December 12 16:06 EST 2018. Contains 318077 sequences. (Running on oeis4.)