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 A134068 a(n) = 2*a(n-2) + 4*a(n-3), with initial terms 0, 3, 3. 1
 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 (list; graph; refs; listen; history; text; internal format)
 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:=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, A134654. 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

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Last modified November 25 14:21 EST 2020. Contains 338624 sequences. (Running on oeis4.)