id:A125070 - OEIS Search Results

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a(n) = number of nonzero exponents in the prime-factorization of n which are not primes.

+0
2

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; listen)

	OFFSET	`1,6`
	LINKS	`Leroy Quet, Home Page (listed in lieu of email address)`
	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.`
	MATHEMATICA	`f[n_] := Length @ Select[Last /@ FactorInteger[n], ! PrimeQ[ # ] &]; Table[f[n], {n, 110}] (Chandler)`
	CROSSREFS	`Cf. A125071.` `Sequence in context: A025874 A050326 A056169 this_sequence A125071 A161528 A136176` `Adjacent sequences: A125067 A125068 A125069 this_sequence A125071 A125072 A125073`
	KEYWORD	`nonn`
	AUTHOR	`Leroy Quet, Nov 18 2006`
	EXTENSIONS	`Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Nov 19 2006`

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Last modified November 24 14:25 EST 2009. Contains 167438 sequences.

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