id:A132421 - OEIS Search Results

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a(n) = LCM of the integers b(k), over all k where 1 <= k <= n, where b(k) = the k-th integer from among those positive integers which are coprime to (n+1-k).

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1, 2, 3, 20, 420, 90, 1155 (list; graph; listen)

	OFFSET	`1,2`
	EXAMPLE	`The integers coprime to 4 are 1,3,5,.. The 1st of these is 1. The integers coprime to 3 are 1,2,4,5,.. The 2nd of these is 2. The integers coprime to 2 are 1,3,5,7,9,.. The 3rd of these is 5. And the integers coprime to 1 are 1,2,3,4,5,.. The 4th of these is 4. So a(5) = LCM(1,2,5,4) = 20.`
	CROSSREFS	`Cf. A130767.` `Sequence in context: A012416 A006246 A110372 this_sequence A132500 A129411 A124447` `Adjacent sequences: A132418 A132419 A132420 this_sequence A132422 A132423 A132424`
	KEYWORD	`more,nonn`
	AUTHOR	`Leroy Quet (qq-quet(AT)mindspring.com), Aug 20 2007`

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Last modified July 25 07:41 EDT 2008. Contains 142293 sequences.

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