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A125070
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a(n) = number of nonzero exponents in the prime-factorization of n which are not primes.
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1
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0, 1, 1, 0, 1, 2, 1, 0, 0, 2, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 2, 2, 1, 1, 0, 2, 0, 1, 1, 3, 1, 0, 2, 2, 2, 0, 1, 2, 2, 1, 1, 3, 1, 1, 1, 2, 1, 2, 0, 1, 2, 1, 1, 1, 2, 1, 2, 2, 1, 2, 1, 2, 1, 1, 2, 3, 1, 1, 2, 3, 1, 0, 1, 2, 1, 1, 2, 3, 1, 2, 1, 2, 1, 2, 2, 2, 2, 1, 1, 2, 2, 1, 2, 2, 2, 1, 1, 1, 1, 0, 1, 3, 1, 1, 3
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,6
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EXAMPLE
| 720 has the prime-factorization of 2^4 *3^2 *5^1. Two of these exponents, 4 and 1, are not primes. So a(720) = 2.
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MATHEMATICA
| f[n_] := Length @ Select[Last /@ FactorInteger[n], ! PrimeQ[ # ] &]; Table[f[n], {n, 110}] (*Chandler*)
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CROSSREFS
| Cf. A125071.
Sequence in context: A025874 A050326 A056169 * A125071 A177207 A161528
Adjacent sequences: A125067 A125068 A125069 * A125071 A125072 A125073
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KEYWORD
| nonn
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AUTHOR
| Leroy Quet, Nov 18 2006
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EXTENSIONS
| Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Nov 19 2006
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