id:A106404 - OEIS Search Results

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Number of even semiprimes dividing n.

+0
3

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

	OFFSET	`1,12`
	COMMENT	`a(n) = A086971(n) - A106405(n);` `a(A100484(n)) = 1;` `a(A005408(n)) = 0; a(A005843(n)) > 0 for n>1.`
	FORMULA	`a(2n) = omega(n), a(2n+1) = 0, where omega(n) is the number of distinct prime divisors of n, A001221. - Frank Adams-Watters (FrankTAW(AT)Netscape.net), Jun 09 2006`
	EXAMPLE	`a(60) = #{4, 6, 10} = #{22, 23, 2*5} = 3.`
	CROSSREFS	`Cf. A001227, A000005.` `Cf. A001221.` `Sequence in context: A157187 A152140 A104975 this_sequence A083889 A127523 A116927` `Adjacent sequences: A106401 A106402 A106403 this_sequence A106405 A106406 A106407`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), May 02 2005`

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Last modified November 23 17:09 EST 2009. Contains 167438 sequences.

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