id:A073539 - OEIS Search Results

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Numbers n such that if p is a prime and divides n then p divides phi(n) (but converse is not a condition for the sequence: phi(n) could have prime factors not dividing n).

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1, 4, 8, 9, 16, 18, 25, 27, 32, 36, 49, 50, 54, 64, 72, 81, 98, 100, 108, 121, 125, 128, 144, 147, 162, 169, 196, 200, 216, 225, 242, 243, 250, 256, 288, 289, 294, 324, 338, 343, 361, 392, 400, 432, 441, 450, 484, 486, 500, 507, 512, 529, 576, 578, 588, 605 (list; graph; listen)

	OFFSET	`1,2`
	EXAMPLE	`98 = 27^2 and phi(98)=23*7 so if p divides 98 then p divides phi(98), hence 98 is in the sequence.`
	CROSSREFS	`Adjacent sequences: A073536 A073537 A073538 this_sequence A073540 A073541 A073542` `Sequence in context: A034024 A140269 A070003 this_sequence A090779 A034038 A069265`
	KEYWORD	`easy,nonn`
	AUTHOR	`Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 27 2002`

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Last modified October 7 08:31 EDT 2008. Contains 144667 sequences.

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