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A325860
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Number of subsets of {1..n} such that every pair of distinct elements has a different quotient.
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21
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1, 2, 4, 8, 14, 28, 52, 104, 188, 308, 548, 1096, 1784, 3568, 6168, 10404, 16200, 32400, 49968, 99936, 155584, 256944, 433736, 867472, 1297504, 2026288, 3387216, 5692056, 8682912, 17365824, 25243200, 50486400, 78433056, 125191968, 206649216, 328195632
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OFFSET
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0,2
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COMMENTS
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Also subsets of {1..n} such that every orderless pair of (not necessarily distinct) elements has a different product.
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LINKS
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EXAMPLE
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The a(0) = 1 through a(4) = 14 subsets:
{} {} {} {} {}
{1} {1} {1} {1}
{2} {2} {2}
{12} {3} {3}
{12} {4}
{13} {12}
{23} {13}
{123} {14}
{23}
{24}
{34}
{123}
{134}
{234}
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MATHEMATICA
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Table[Length[Select[Subsets[Range[n]], UnsameQ@@Divide@@@Subsets[#, {2}]&]], {n, 0, 20}]
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CROSSREFS
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The integer partition case is A325853.
The strict integer partition case is A325854.
Heinz numbers of the counterexamples are given by A325994.
Cf. A002033, A108917, A143823, A196723, A196723, A196724, A325855, A325858, A325859, A325868, A325869.
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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