A168213 a(n) = (11 + 18*n + 9*(-1)^n)/4.

5, 14, 14, 23, 23, 32, 32, 41, 41, 50, 50, 59, 59, 68, 68, 77, 77, 86, 86, 95, 95, 104, 104, 113, 113, 122, 122, 131, 131, 140, 140, 149, 149, 158, 158, 167, 167, 176, 176, 185, 185, 194, 194, 203, 203, 212, 212, 221, 221, 230, 230, 239, 239, 248, 248, 257, 257

Offset

1,1

Comments

Essentially the same as A168418.

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 R. J. Mathar, Jan 05 2011: (Start)

a(n) = 9*n - a(n-1) + 1 for n > 1.

G.f.: x*(5 + 9*x - 5*x^2)/( (1+x)*(x-1)^2 ). (End)

E.g.f.: (1/4)*(9 - 20*exp(x) + (11 + 18*x)*exp(2*x))*exp(-x). - G. C. Greubel, Jul 16 2016

a(n) = a(n-1) + a(n-2) - a(n-3). - Wesley Ivan Hurt, Aug 17 2021

Maple

A168213:=n->(11 + 18*n + 9*(-1)^n)/4: seq(A168213(n), n=1..100); # Wesley Ivan Hurt, Apr 26 2017

Mathematica

LinearRecurrence[{1, 1, -1}, {5, 14, 14}, 60] (* Vincenzo Librandi, Feb 28 2012 *)

Prog

(Magma) I:=[5, 14, 14]; [n le 3 select I[n] else Self(n-1)+Self(n-2)-Self(n-3): n in [1..40]]; // Vincenzo Librandi, Feb 28 2012
(PARI) a(n)=(11+18*n+9*(-1)^n)/4 \\ Charles R Greathouse IV, Jul 16 2016

Crossrefs

Cf. A168418.

Sequence in context: A196363 A169811 A272970 * A175485 A174657 A231665

Adjacent sequences: A168210 A168211 A168212 * A168214 A168215 A168216

Keyword

nonn,easy

Author

Vincenzo Librandi, Nov 20 2009

Status

approved