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A285572
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Number of finite sets of pairwise indivisible positive integers with least common multiple n.
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69
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1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 3, 1, 2, 2, 1, 1, 3, 1, 3, 2, 2, 1, 4, 1, 2, 1, 3, 1, 9, 1, 1, 2, 2, 2, 6, 1, 2, 2, 4, 1, 9, 1, 3, 3, 2, 1, 5, 1, 3, 2, 3, 1, 4, 2, 4, 2, 2, 1, 23, 1, 2, 3, 1, 2, 9, 1, 3, 2, 9, 1, 10, 1, 2, 3, 3, 2, 9, 1, 5, 1, 2, 1, 23, 2, 2, 2, 4, 1, 23, 2, 3, 2, 2, 2, 6, 1, 3, 3, 6
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OFFSET
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1,6
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LINKS
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Michael De Vlieger, Table of n, a(n) for n = 1..10000
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EXAMPLE
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The a(72)=10 sets are {72}, {8,9}, {8,18}, {8,36}, {9,24}, {18,24}, {24,36}, {6,8,9}, {8,9,12}, {8,12,18}.
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MATHEMATICA
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nn=50;
stableSets[u_, Q_]:=If[Length[u]===0, {{}}, With[{w=First[u]}, Join[stableSets[DeleteCases[u, w], Q], Prepend[#, w]&/@stableSets[DeleteCases[u, r_/; r===w||Q[r, w]||Q[w, r]], Q]]]];
Table[Length[Select[Rest[stableSets[Divisors[n], Divisible]], LCM@@#===n&]], {n, 1, nn}]
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CROSSREFS
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Cf. A000666, A006126, A048143, A054921, A076078, A076413, A285573.
Sequence in context: A168324 A303838 A324837 * A179926 A066882 A300831
Adjacent sequences: A285569 A285570 A285571 * A285573 A285574 A285575
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KEYWORD
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nonn
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AUTHOR
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Gus Wiseman, Apr 21 2017
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STATUS
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approved
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