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A099216
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a(n)=4a(n-1)-4a(n-2)+2a(n-3).
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2
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1, 2, 4, 10, 28, 80, 228, 648, 1840, 5224, 14832, 42112, 119568, 339488, 963904, 2736800, 7770560, 22062848, 62642752, 177860736, 504997632, 1433833088, 4071063296, 11558916096, 32819077376, 93182771712, 264572609536
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OFFSET
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0,2
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COMMENTS
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Binomial transform of tribonacci numbers A000213.
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LINKS
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FORMULA
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G.f.: (1-2x)/((1-2x)^2-2x^3); a(n)=sum{k=0..floor(n/3), binomial(n-k, 2k)2^k*2^(n-3k)}.
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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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