id:A120837 - OEIS Search Results

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A120837

a(n) = the smallest positive integer which does not occur earlier in the sequence and which is coprime to the number of positive divisors of n.

+0
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1, 3, 5, 2, 7, 9, 11, 13, 4, 15, 17, 19, 21, 23, 25, 6, 27, 29, 31, 35, 33, 37, 39, 41, 8, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 10, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 87, 14, 85, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107, 109, 111, 113, 12, 115, 117, 119, 121 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Sequence is a permutation of the positive integers.`
	LINKS	`Leroy Quet, Home Page (listed in lieu of email address)`
	EXAMPLE	`6 has 4 positive divisors. Among those positive integers not occurring among the first 5 terms of the sequence, 9 is the smallest which is coprime to 4. So a(6) = 9. 4, 6 and 8 also do not occur among the first 5 terms of the sequence, but they are not coprime to 4.`
	CROSSREFS	`Cf. A000005.` `Sequence in context: A125132 A026184 A026208 this_sequence A095749 A137988 A160092` `Adjacent sequences: A120834 A120835 A120836 this_sequence A120838 A120839 A120840`
	KEYWORD	`nonn`
	AUTHOR	`Leroy Quet Aug 18 2006`
	EXTENSIONS	`Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Aug 22 2006`

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Last modified November 25 08:46 EST 2009. Contains 167481 sequences.

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