id:A125029 - OEIS Search Results

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a(n) = number of exponents in the prime-factorization of n which are noncomposite.

+0
2

0, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 2, 0, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 1, 2, 1, 3, 1, 1, 2, 2, 2, 2, 1, 2, 2, 2, 1, 3, 1, 2, 2, 2, 1, 1, 1, 2, 2, 2, 1, 2, 2, 2, 2, 2, 1, 3, 1, 2, 2, 0, 2, 3, 1, 2, 2, 3, 1, 2, 1, 2, 2, 2, 2, 3, 1, 1, 0, 2, 1, 3, 2, 2, 2, 2, 1, 3, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 1, 3, 1, 2, 3 (list; graph; listen)

	OFFSET	`1,6`
	EXAMPLE	`a(720) = 2, 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).`
	MATHEMATICA	`f[n_] := Length @ Select[Last /@ FactorInteger[n], # == 1 \|\| PrimeQ[ # ] &]; Table[f[n], {n, 110}] (Chandler)`
	CROSSREFS	`Cf. A125030.` `Sequence in context: A126864 A124766 A103765 this_sequence A062893 A087802 A079553` `Adjacent sequences: A125026 A125027 A125028 this_sequence A125030 A125031 A125032`
	KEYWORD	`nonn`
	AUTHOR	`Leroy Quet (qq-quet(AT)mindspring.com), Nov 16 2006`
	EXTENSIONS	`Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Nov 19 2006`

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Last modified September 6 09:40 EDT 2008. Contains 143480 sequences.

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