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A121550
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Number of ordered ways of writing n as a sum of three Fibonacci numbers (only one 1 is considered as a Fibonacci number).
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13
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0, 0, 1, 3, 6, 7, 9, 9, 10, 9, 12, 12, 9, 9, 10, 12, 12, 12, 12, 6, 9, 6, 12, 13, 9, 12, 12, 9, 12, 6, 12, 6, 0, 9, 6, 9, 15, 9, 13, 9, 6, 12, 9, 12, 9, 0, 12, 6, 6, 12, 0, 6, 0, 0, 9, 6, 9, 12, 9, 15, 9, 6, 13, 6, 9, 6, 0, 12, 9, 9, 12, 0, 9, 0, 0, 12, 6, 6, 6, 0, 12, 0, 0, 6, 0, 0, 0, 0, 9, 6, 9, 12
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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.: (Sum_{i>=2} x^Fibonacci(i))^3.
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EXAMPLE
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a(6)=7 because we have 6=1+2+3=1+3+2=2+1+3=2+3+1=3+1+2=3+2+1=2+2+2.
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MAPLE
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with(combinat): g:=sum(z^fibonacci(i), i=2..30)^3: gser:=series(g, z=0, 130): seq(coeff(gser, z, n), n=1..126);
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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