id:A144741 - OEIS Search Results

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Partial cototient function Phi(c, n) for c = 2: number of semiprimes less than or equal and not coprime to n.

+0
5

0, 0, 0, 1, 0, 2, 0, 2, 2, 3, 0, 4, 0, 4, 4, 4, 0, 6, 0, 5, 5, 5, 0, 8, 3, 6, 4, 7, 0, 10, 0, 6, 6, 7, 6, 11, 0, 8, 7, 11, 0, 14, 0, 9, 9, 9, 0, 14, 4, 12, 8, 10, 0, 15, 7, 12, 9, 10, 0, 20, 0, 11, 11, 11, 8, 19, 0, 12, 10, 18, 0, 19, 0, 12, 14, 13, 8, 21, 0, 17, 9, 13, 0, 24, 9, 14, 11, 17, 0, 28, 9 (list; graph; listen)

	OFFSET	`1,6`
	EXAMPLE	`Phi(2, 4) = 1: four is a semiprime.` `Phi(2, 10) = 3: four, six and ten are semiprimes; nine is a semiprime relatively prime to ten.`
	CROSSREFS	`Cf. A000010, A144740` `Sequence in context: A103863 A166395 A061199 this_sequence A103615 A159632 A164733` `Adjacent sequences: A144738 A144739 A144740 this_sequence A144742 A144743 A144744`
	KEYWORD	`easy,nonn`
	AUTHOR	`Reikku Kulon (reikku(AT)gmail.com), Sep 20 2008`

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Last modified December 1 13:27 EST 2009. Contains 167806 sequences.

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