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A187490
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Number of 3-element nondividing subsets of {1, 2, ..., n}.
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2
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1, 2, 6, 12, 22, 31, 49, 70, 99, 128, 176, 216, 284, 343, 423, 515, 633, 722, 860, 1007, 1173, 1333, 1552, 1729, 1989, 2223, 2502, 2809, 3138, 3416, 3819, 4226, 4658, 5049, 5570, 6016, 6601, 7146, 7719, 8371, 9100, 9686, 10461, 11208, 12039
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OFFSET
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7,2
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COMMENTS
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A set is called nondividing if no element divides the sum of any nonempty subset of the other elements.
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LINKS
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EXAMPLE
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a(7) = 1 because there is one 3-element nondividing subset of {1,2,3,4,5,6,7}: {4,6,7}.
a(9) = 6: {4,6,7}, {4,6,9}, {5,6,8}, {5,8,9}, {6,7,9}, {6,8,9}.
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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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