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A121720
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a(n) = 4*a(n-2) - 2*a(n-4).
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0
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0, 1, 1, 3, 4, 10, 14, 34, 48, 116, 164, 396, 560, 1352, 1912, 4616, 6528, 15760, 22288, 53808, 76096, 183712, 259808, 627232, 887040, 2141504, 3028544, 7311552, 10340096, 24963200, 35303296, 85229696, 120532992, 290992384, 411525376, 993510144, 1405035520
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OFFSET
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1,4
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LINKS
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FORMULA
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G.f.: -x^2*(-1-x+x^2)/(1-4*x^2+2*x^4). [Oct 14 2009]
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MATHEMATICA
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LinearRecurrence[{0, 4, 0, -2}, {0, 1, 1, 3}, 30] (* Harvey P. Dale, May 21 2014 *)
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CROSSREFS
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KEYWORD
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nonn,easy,less
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AUTHOR
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EXTENSIONS
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Definition replaced by recurrence - The Assoc. Editors of the OEIS, Oct 14 2009
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STATUS
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approved
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