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A200563
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Expansion of -2*x*(1+4*x) / ((2*x-1)*(4*x^2+3*x+1)).
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1
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2, 6, -2, 30, 14, 30, 238, -66, 782, 990, 46, 8190, -178, 16926, 48238, -15810, 247694, 106590, 262318, 1932414, -555058, 6518430, 7830766, 765630, 67043342, -2865954, 143077678, 387537150, -124309426, 2044005150, 807673198, 2285861694, 15681525902, -4648416930
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OFFSET
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1,1
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LINKS
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FORMULA
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a(n) = -a(n-1) +2*a(n-2) +8*a(n-3).
a(n) = (6*4^n+r^(n+1)+(16/r)^(n+1))/(7*2^n), where r=-3-sqrt(-7). - Bruno Berselli, Dec 12 2011
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MATHEMATICA
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LinearRecurrence[{-1, 2, 8}, {2, 6, -2}, 34] (* Bruno Berselli, Dec 12 2011 *)
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PROG
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(Maxima) makelist(expand((6*4^n+(-3-sqrt(-7))^(n+1)+(-3+sqrt(-7))^(n+1))/(7*2^n)), n, 1, 34); /* Bruno Berselli, Dec 12 2011 */
(Magma) I:=[2, 6, -2]; [n le 3 select I[n] else -Self(n-1)+2*Self(n-2)+8*Self(n-3): n in [1..40]]; // Vincenzo Librandi, Jul 12 2012
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CROSSREFS
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KEYWORD
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sign,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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