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A331230
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Numbers k such that the number of factorizations of k into distinct factors > 1 is odd.
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3
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1, 2, 3, 4, 5, 7, 9, 11, 12, 13, 17, 18, 19, 20, 23, 24, 25, 28, 29, 30, 31, 32, 36, 37, 40, 41, 42, 43, 44, 45, 47, 48, 49, 50, 52, 53, 54, 56, 59, 60, 61, 63, 66, 67, 68, 70, 71, 72, 73, 75, 76, 78, 79, 80, 83, 84, 88, 89, 90, 92, 97, 98, 99, 100, 101, 102
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OFFSET
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1,2
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COMMENTS
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First differs from A319237 in lacking 300.
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LINKS
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MATHEMATICA
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strfacs[n_]:=If[n<=1, {{}}, Join@@Table[Map[Prepend[#, d]&, Select[strfacs[n/d], Min@@#>d&]], {d, Rest[Divisors[n]]}]];
Select[Range[100], OddQ[Length[strfacs[#]]]&]
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CROSSREFS
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The version for strict integer partitions is A001318.
The version for integer partitions is A052002.
The version for set partitions appears to be A032766.
The version for primes (instead of odds) is A331201.
The least number with n strict factorizations is A330974(n).
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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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