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