id:A070547 - OEIS Search Results

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a(n)=Card( k, 0<k<n such that phi(k) divides phi(n-k)).

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0, 1, 2, 2, 2, 3, 4, 4, 5, 6, 5, 5, 7, 6, 7, 8, 7, 9, 5, 10, 9, 10, 9, 7, 11, 9, 10, 10, 8, 9, 10, 11, 13, 12, 12, 13, 11, 11, 12, 14, 12, 13, 8, 16, 15, 16, 15, 11, 19, 16, 12, 15, 11, 16, 15, 17, 16, 15, 10, 14, 15, 12, 20, 15, 20, 18, 11, 17, 16, 18, 16, 18, 15, 18, 18, 16, 18 (list; graph; listen)

	OFFSET	`1,3`
	PROGRAM	`(PARI) for(n=1, 100, print1(sum(i=1, n-1, if(eulerphi(n-i)%eulerphi(i), 0, 1)), ", "))`
	CROSSREFS	`Sequence in context: A029113 A105098 A063124 this_sequence A094838 A025768 A000929` `Adjacent sequences: A070544 A070545 A070546 this_sequence A070548 A070549 A070550`
	KEYWORD	`easy,nonn`
	AUTHOR	`Benoit Cloitre (benoit7848c(AT)orange.fr), May 02 2002`

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Last modified July 6 17:22 EDT 2008. Contains 140988 sequences.

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