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A071386
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Numbers k such that the cardinality of the set of solutions to phi(x) = k is odd.
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6
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2, 8, 20, 32, 40, 44, 48, 56, 60, 72, 92, 96, 104, 108, 116, 120, 128, 132, 140, 144, 156, 164, 192, 204, 212, 216, 220, 240, 252, 260, 272, 276, 296, 300, 332, 344, 356, 360, 368, 380, 384, 392, 396, 400, 416, 420, 440, 444, 452, 456, 476, 480, 500, 504, 512
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OFFSET
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1,1
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LINKS
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FORMULA
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{ k : Card(InvPhi(k)) mod 2 = 1 }.
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EXAMPLE
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k = 40 is a term: InvPhi(40) = {41,55,75,82,88,100,110,132,150} has 9 entries.
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PROG
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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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