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A097336
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Sum k=0..n, C(n-k, floor(k/2))4^k.
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1
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1, 5, 5, 21, 101, 181, 517, 2133, 5029, 13301, 47429, 127893, 340709, 1099573, 3145861, 8597205, 26190373, 76524149, 214079429, 633125397, 1857511781, 5282782645, 15412788997, 45132977493, 129657499813, 376262123765
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OFFSET
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0,2
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COMMENTS
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The sequence sum{k=0..n, C(n-k,floor(k/2))r^k} has g.f. (1+rx)/(1-x-r^2x^3).
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LINKS
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FORMULA
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G.f. : (1+4x)/(1-x-16x^3); a(n)=a(n-1)+16a(n-3).
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MATHEMATICA
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LinearRecurrence[{1, 0, 16}, {1, 5, 5}, 30] (* Harvey P. Dale, Sep 15 2011 *)
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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