id:A109606 - OEIS Search Results

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a(n) = number of numbers k with 1 < k < n which are relatively prime to n.

+0
3

0, 0, 0, 1, 1, 3, 1, 5, 3, 5, 3, 9, 3, 11, 5, 7, 7, 15, 5, 17, 7, 11, 9, 21, 7, 19, 11, 17, 11, 27, 7, 29, 15, 19, 15, 23, 11, 35, 17, 23, 15, 39, 11, 41, 19, 23, 21, 45, 15, 41, 19, 31, 23, 51, 17, 39, 23, 35, 27, 57, 15, 59, 29, 35, 31, 47, 19, 65, 31, 43, 23, 69, 23, 71, 35, 39, 35 (list; graph; listen)

	OFFSET	`0,6`
	FORMULA	`a(n) = phi(n)-1.`
	EXAMPLE	`a(9) = 5 because 2,4,5,7,8 are coprime to 9`
	CROSSREFS	`Cf. A000010.` `Sequence in context: A143865 A071168 A091926 this_sequence A127418 A099550 A099549` `Adjacent sequences: A109603 A109604 A109605 this_sequence A109607 A109608 A109609`
	KEYWORD	`nonn`
	AUTHOR	`Andrew Weimholt (andrew(AT)weimholt.com), Jul 31 2005`
	EXTENSIONS	`Definition modified by Reinhard Zumkeller, Mar 03 2009`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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