A134068 a(n) = 2*a(n-2) + 4*a(n-3), with initial terms 0, 3, 3.

0, 3, 3, 6, 18, 24, 60, 120, 216, 480, 912, 1824, 3744, 7296, 14784, 29568, 58752, 118272, 235776, 471552, 944640, 1886208, 3775488, 7550976, 15095808, 30203904, 60395520, 120791040, 241606656, 483164160, 966377472, 1932754944, 3865411584, 7731019776, 15461842944

Offset: 0

Author

Paul Curtz, Jan 29 2008

Keywords

• nonn

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (0,2,4).

Crossrefs

Cf. A134136, A038521.

Programs

Magma

a:=[0,3,3]; [n le 3 select a[n] else 2*Self(n-2) + 4*Self(n-3):n in [1..35]]; // Marius A. Burtea, Jan 03 2020

Magma

R:=PowerSeriesRing(Integers(), 35); [0] cat Coefficients(R!( 3*x*(1 + x)/((1 - 2*x)*(1 + 2*x + 2*x^2)))); // Marius A. Burtea, Jan 03 2020

PARI

concat([0], Vec(3*(1 + x)/((1 - 2*x)*(1 + 2*x + 2*x^2)) + O(x^40))) \\ Andrew Howroyd, Jan 03 2020

Formula

From Andrew Howroyd, Jan 03 2020: (Start)

G.f.: 3*x*(1 + x)/((1 - 2*x)*(1 + 2*x + 2*x^2)).

a(n) = 3*A134136(n). (End)

Extensions

a(12) corrected and terms a(13) and beyond from Andrew Howroyd, Jan 03 2020