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A326496
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Number of maximal product-free subsets of {1..n}.
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12
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1, 1, 1, 1, 2, 2, 3, 3, 3, 4, 6, 6, 9, 9, 15, 17, 30, 30, 46, 46, 51, 61, 103, 103, 129, 158, 282, 282, 322, 322, 553, 553, 615, 689, 1247, 1365, 1870, 1870, 3566, 3758, 5244, 5244, 8677, 8677, 9807, 12147, 23351, 23351, 27469, 31694, 45718, 47186, 54594, 54594, 95382, 108198
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OFFSET
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0,5
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COMMENTS
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A set is product-free if it contains no product of two (not necessarily distinct) elements.
Also the number of maximal quotient-free subsets of {1..n}.
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LINKS
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EXAMPLE
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The a(2) = 1 through a(10) = 6 subsets (A = 10):
{2} {23} {23} {235} {235} {2357} {23578} {23578} {23578}
{34} {345} {256} {2567} {25678} {256789} {2378A}
{3456} {34567} {345678} {345678} {256789}
{456789} {26789A}
{345678A}
{456789A}
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MATHEMATICA
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fasmax[y_]:=Complement[y, Union@@(Most[Subsets[#]]&/@y)];
Table[Length[fasmax[Select[Subsets[Range[n]], Intersection[#, Times@@@Tuples[#, 2]]=={}&]]], {n, 0, 10}]
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PROG
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(PARI) \\ See link for program file.
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CROSSREFS
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Subsets without products of distinct elements are A326117.
Maximal sum-free subsets are A121269.
Maximal sum-free and product-free subsets are A326497.
Maximal subsets without products of distinct elements are A325710.
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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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