A166621 a(n) = 10*n - a(n-1), with n>1, a(1)=5.

5, 15, 15, 25, 25, 35, 35, 45, 45, 55, 55, 65, 65, 75, 75, 85, 85, 95, 95, 105, 105, 115, 115, 125, 125, 135, 135, 145, 145, 155, 155, 165, 165, 175, 175, 185, 185, 195, 195, 205, 205, 215, 215, 225, 225, 235, 235, 245, 245, 255, 255, 265, 265, 275, 275, 285

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (1,1,-1).

Formula

From Vincenzo Librandi, Sep 15 2013: (Start)

G.f.: -x*(-5-10*x+5*x^2)/((1+x)*(x-1)^2).

a(n) = a(n-1) + a(n-2) - a(n-3). (End)

E.g.f.: 5*((1+x)*cosh(x) + x*sinh(x) - 1). - G. C. Greubel, May 18 2016

Mathematica

RecurrenceTable[{a[1]==5, a[n]==10n-a[n-1]}, a, {n, 60}] (* or *) CoefficientList[Series[-(- 5 - 10 x + 5 x^2) /((1 + x) (x - 1)^2), {x, 0, 60}], x] (* Vincenzo Librandi, Sep 15 2013 *)

Prog

(Magma) [n le 1 select (n+4) else 10*n-Self(n-1): n in [1..70] ]; // Vincenzo Librandi, Sep 15 2013

Crossrefs

Sequence in context: A309620 A291794 A321775 * A330082 A160275 A200858

Adjacent sequences: A166618 A166619 A166620 * A166622 A166623 A166624

Keyword

nonn,easy

Author

Vincenzo Librandi, Oct 18 2009

Status

approved