A176448 a(n) = 7*2^n - 2.

5, 12, 26, 54, 110, 222, 446, 894, 1790, 3582, 7166, 14334, 28670, 57342, 114686, 229374, 458750, 917502, 1835006, 3670014, 7340030, 14680062, 29360126, 58720254, 117440510, 234881022, 469762046, 939524094, 1879048190, 3758096382

Offset

0,1

Comments

a(n) = 2*A086224(n-1) for n > 0 [Berselli - Librandi]. - Vincenzo Librandi, Aug 27 2010

Links

Table of n, a(n) for n=0..29.

Index entries for linear recurrences with constant coefficients, signature (3,-2).

Formula

a(n) = 2*(a(n-1) + 1) with a(0)=5.

From R. J. Mathar, May 02 2010: (Start)

a(n)= 3*a(n-1) - 2*a(n-2).

G.f.: ( 5-3*x ) / ( (2*x-1)*(x-1) ). (End)

a(n) = A174317(n+3). - R. J. Mathar, Feb 21 2016

Example

a(1) = 2*(5 + 1) = 12;
a(2) = 2*(12 + 1) = 26;
a(3) = 2*(26 + 1) = 54.

Mathematica

Table[7*2^n-2, {n, 0, 30}] (* or *) LinearRecurrence[{3, -2}, {5, 12}, 30] (* Harvey P. Dale, May 21 2017 *)

Prog

(Magma) [7*2^n-2: n in [0..100]]

Crossrefs

Sequence in context: A212561 A199771 A200252 * A078517 A170828 A357417

Adjacent sequences: A176445 A176446 A176447 * A176449 A176450 A176451

Keyword

nonn,easy

Author

Vincenzo Librandi, Apr 18 2010

Status

approved