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A125030
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a(n) = sum of exponents in the prime-factorization of n which are noncomposite.
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1
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0, 1, 1, 2, 1, 2, 1, 3, 2, 2, 1, 3, 1, 2, 2, 0, 1, 3, 1, 3, 2, 2, 1, 4, 2, 2, 3, 3, 1, 3, 1, 5, 2, 2, 2, 4, 1, 2, 2, 4, 1, 3, 1, 3, 3, 2, 1, 1, 2, 3, 2, 3, 1, 4, 2, 4, 2, 2, 1, 4, 1, 2, 3, 0, 2, 3, 1, 3, 2, 3, 1, 5, 1, 2, 3, 3, 2, 3, 1, 1, 0, 2, 1, 4, 2, 2, 2, 4, 1, 4, 2, 3, 2, 2, 2, 6, 1, 3, 3, 4, 1, 3, 1, 4, 3
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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EXAMPLE
| a(720) = 3, since the prime-factorization of 720 is 2^4 *3^2 *5^1 and 2 of the exponents in this factorization are non-composites (the exponents 2 and 1, which when added is 3).
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MATHEMATICA
| f[n_] := Plus @@ Select[Last /@ FactorInteger[n], # == 1 || PrimeQ[ # ] &]; Table[f[n], {n, 110}] (*Chandler*)
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CROSSREFS
| Cf. A125029.
Sequence in context: A147810 A055181 A073811 * A116479 A122810 A179953
Adjacent sequences: A125027 A125028 A125029 * A125031 A125032 A125033
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KEYWORD
| nonn
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AUTHOR
| Leroy Quet, Nov 16 2006
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EXTENSIONS
| Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Nov 19 2006
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