A168211 a(n) = (9 + 14*n + 23*(-1)^n)/4.

0, 15, 7, 22, 14, 29, 21, 36, 28, 43, 35, 50, 42, 57, 49, 64, 56, 71, 63, 78, 70, 85, 77, 92, 84, 99, 91, 106, 98, 113, 105, 120, 112, 127, 119, 134, 126, 141, 133, 148, 140, 155, 147, 162, 154, 169, 161, 176, 168, 183, 175, 190, 182, 197, 189, 204, 196, 211, 203

Offset

1,2

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

G.f.: x^2*(15 - 8*x) / ( (1+x)*(x-1)^2 ). - R. J. Mathar, Jan 05 2011

a(n) = a(n-1) +a(n-2) -a(n-3). - Vincenzo Librandi, - Feb 28 2012

E.g.f.: (1/4)*(23 - 32*exp(x) + (9 +14*x)*exp(2*x))*exp(-x). - G. C. Greubel, Jul 15 2016

Mathematica

LinearRecurrence[{1, 1, -1}, {0, 15, 7}, 50] (* Vincenzo Librandi, Feb 28 2012 *)

Prog

(Magma) I:=[0, 15, 7]; [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

Crossrefs

Sequence in context: A240909 A133817 A173447 * A131876 A325136 A126070

Adjacent sequences: A168208 A168209 A168210 * A168212 A168213 A168214

Keyword

nonn,easy

Author

Vincenzo Librandi, Nov 20 2009

Status

approved