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A336424
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Number of factorizations of n where each factor belongs to A130091 (numbers with distinct prime multiplicities).
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25
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1, 1, 1, 2, 1, 1, 1, 3, 2, 1, 1, 3, 1, 1, 1, 5, 1, 3, 1, 3, 1, 1, 1, 5, 2, 1, 3, 3, 1, 1, 1, 7, 1, 1, 1, 6, 1, 1, 1, 5, 1, 1, 1, 3, 3, 1, 1, 9, 2, 3, 1, 3, 1, 5, 1, 5, 1, 1, 1, 4, 1, 1, 3, 11, 1, 1, 1, 3, 1, 1, 1, 11, 1, 1, 3, 3, 1, 1, 1, 9, 5, 1, 1, 4, 1, 1
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OFFSET
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1,4
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COMMENTS
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A number's prime signature (row n of A124010) is the sequence of positive exponents in its prime factorization, so a number has distinct prime multiplicities iff all the exponents in its prime signature are distinct.
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LINKS
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EXAMPLE
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The a(n) factorizations for n = 2, 4, 8, 60, 16, 36, 32, 48:
2 4 8 5*12 16 4*9 32 48
2*2 2*4 3*20 4*4 3*12 4*8 4*12
2*2*2 3*4*5 2*8 3*3*4 2*16 3*16
2*2*3*5 2*2*4 2*18 2*4*4 3*4*4
2*2*2*2 2*2*9 2*2*8 2*24
2*2*3*3 2*2*2*4 2*3*8
2*2*2*2*2 2*2*12
2*2*3*4
2*2*2*2*3
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MATHEMATICA
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facsusing[s_, n_]:=If[n<=1, {{}}, Join@@Table[Map[Prepend[#, d]&, Select[facsusing[Select[s, Divisible[n/d, #]&], n/d], Min@@#>=d&]], {d, Select[s, Divisible[n, #]&]}]];
Table[Length[facsusing[Select[Range[2, n], UnsameQ@@Last/@FactorInteger[#]&], n]], {n, 100}]
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CROSSREFS
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A007425 counts divisors of divisors.
A045778 counts strict factorizations.
A074206 counts ordered factorizations.
A130091 lists numbers with distinct prime multiplicities.
A181796 counts divisors with distinct prime multiplicities.
A253249 counts nonempty chains of divisors.
A281116 counts factorizations with no common divisor.
A302696 lists numbers whose prime indices are pairwise coprime.
A305149 counts stable factorizations.
A327498 gives the maximum divisor with distinct prime multiplicities.
A336568 = not a product of two numbers with distinct prime multiplicities.
Cf. A071625, A080688, A098859, A118914, A124010, A167865, A294068, A303707, A305150, A322453, A336420, A336570, A336571.
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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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