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A081327
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Smallest 3-smooth number m such that n-m is also 3-smooth, a(n)=0 if no such 3-smooth number exists.
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3
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0, 1, 1, 1, 1, 2, 1, 2, 1, 1, 2, 3, 1, 2, 3, 4, 1, 2, 1, 2, 3, 4, 0, 6, 1, 2, 3, 1, 2, 3, 4, 8, 1, 2, 3, 4, 1, 2, 3, 4, 9, 6, 16, 8, 9, 0, 0, 12, 1, 2, 3, 4, 0, 6, 1, 2, 3, 4, 27, 6, 0, 8, 9, 16, 1, 2, 3, 4, 0, 6, 0, 8, 1, 2, 3, 4, 0, 6, 0, 8, 9, 1, 2, 3, 4, 32, 6, 16, 8, 9, 27, 0, 12, 0, 0, 24, 1, 2, 3, 4, 0
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OFFSET
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1,6
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LINKS
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FORMULA
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EXAMPLE
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a(32) = 8 = 2^3, as 32 = 8 + 3*2^3.
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MATHEMATICA
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smooth3Q[n_] := n/2^IntegerExponent[n, 2]/3^IntegerExponent[n, 3] == 1;
a[n_] := Module[{m}, For[m = 1, m<n, m++, If[smooth3Q[m] && smooth3Q[n-m], Return[m]]]; 0];
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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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