id:A069208 - OEIS Search Results

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Sum_{ d divides n } phi(n)/phi(d).

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1, 2, 3, 5, 5, 6, 7, 11, 10, 10, 11, 15, 13, 14, 15, 23, 17, 20, 19, 25, 21, 22, 23, 33, 26, 26, 31, 35, 29, 30, 31, 47, 33, 34, 35, 50, 37, 38, 39, 55, 41, 42, 43, 55, 50, 46, 47, 69, 50, 52, 51, 65, 53, 62, 55, 77, 57, 58, 59, 75, 61, 62, 70, 95, 65, 66, 67, 85, 69, 70, 71 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`a(n) = n iff n is square-free number(cf. A005117).`
	FORMULA	`Multiplicative with a(p^e) = (p^(e+1)-p^e+p^(e-1)-1)/(p-1).`
	CROSSREFS	`Cf. A000010, A069170.` `Adjacent sequences: A069205 A069206 A069207 this_sequence A069209 A069210 A069211` `Sequence in context: A076752 A079114 A058189 this_sequence A066113 A081836 A002334`
	KEYWORD	`nonn,mult`
	AUTHOR	`Vladeta Jovovic (vladeta(AT)Eunet.yu), Apr 10 2002`

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Last modified May 16 23:01 EDT 2008. Contains 139884 sequences.

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