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A164039 a(n+1) = 3*a(n) - n. 4
1, 2, 4, 9, 23, 64, 186, 551, 1645, 4926, 14768, 44293, 132867, 398588, 1195750, 3587235, 10761689, 32285050, 96855132, 290565377, 871696111, 2615088312, 7845264914, 23535794719, 70607384133, 211822152374, 635466457096 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (5,-7,3).

FORMULA

a(0) = 1; a(n+1) = 3*a(n) - n.

a(n) = (3^n + 2*n + 3)/4.

From R. J. Mathar, Aug 09 2009: (Start)

a(n) = 5*a(n-1)-7*a(n-2)+3*a(n-3).

G.f.: (1-3*x+x^2)/((1-3*x)*(1-x)^2). (End)

E.g.f.: (1/4)*((2*x + 3)*exp(x) + exp(3*x)). - G. C. Greubel, Sep 08 2017

MATHEMATICA

Transpose[NestList[Flatten[{Rest[#], ListCorrelate[#, {3, -7, 5}]}]&, {1, 2, 4}, 30]][[1]] (* Harvey P. Dale, Mar 24 2011 *)

Table[(3^n + 2*n + 3)/4, {n, 0, 50}] (* G. C. Greubel, Sep 08 2017 *)

PROG

(PARI) x='x+O('x^50); Vec((1-3*x+x^2)/((1-3*x)*(1-x)^2)) \\ G. C. Greubel, Sep 08 2017

CROSSREFS

Sequence in context: A135307 A000083 A092668 * A014137 A245158 A245159

Adjacent sequences:  A164036 A164037 A164038 * A164040 A164041 A164042

KEYWORD

nonn,easy

AUTHOR

Rolf Pleisch, Aug 08 2009

STATUS

approved

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Last modified February 25 16:14 EST 2018. Contains 299653 sequences. (Running on oeis4.)