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

0,2

Links

Andrew Howroyd, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (0,2,4).

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)

Prog

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

Crossrefs

Cf. A134136, A038521.

Sequence in context: A038076 A123286 A132818 * A025256 A052560 A147836

Adjacent sequences: A134065 A134066 A134067 * A134069 A134070 A134071

Keyword

nonn

Author

Paul Curtz, Jan 29 2008

Extensions

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

Status

approved