A140788 a(n) = 6*4^n + 2.

8, 26, 98, 386, 1538, 6146, 24578, 98306, 393218, 1572866, 6291458, 25165826, 100663298, 402653186, 1610612738, 6442450946, 25769803778, 103079215106, 412316860418, 1649267441666, 6597069766658, 26388279066626, 105553116266498, 422212465065986, 1688849860263938

Offset: 0

Author

Paul Curtz, Jul 14 2008

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (5,-4).

Crossrefs

Cf. A140660.

Programs

Magma

[6*4^n+2: n in [0..30]]; // Vincenzo Librandi, Aug 08 2011

Mathematica

6*4^Range[0,30]+2 (* or *) LinearRecurrence[{5,-4},{8,26},30] (* Harvey P. Dale, Apr 15 2019 *)

Formula

a(n) = 2*A140660(n).

From R. J. Mathar, Feb 07 2009: (Start)

a(n) = 5*a(n-1) - 4*a(n-2).

G.f.: 2*(4-7*x)/((1-x)*(1-4*x)). (End)

E.g.f.: 2*exp(x)*(3*exp(3*x) + 1). - Elmo R. Oliveira, Apr 02 2025

Extensions

More terms from R. J. Mathar, Feb 07 2009