id:A141718 - OEIS Search Results

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Numbers n such that the set of prime divisors of n is equal to the set of prime divisors of phi(n).

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3

1, 4, 8, 16, 18, 32, 36, 50, 54, 64, 72, 100, 108, 128, 144, 162, 200, 216, 250, 256, 288, 294, 324, 400, 432, 450, 486, 500, 512, 576, 578, 588, 648, 800, 864, 882, 900, 972, 1000, 1014, 1024, 1152, 1156, 1176, 1210, 1250, 1296, 1350, 1458, 1600, 1728, 1764 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`All composite numbers of the form 2^m are in the sequence.` `Essentially the same as A055744. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 27 2008]`
	LINKS	`T. D. Noe, Table of n, a(n) for n=1..1000`
	EXAMPLE	`2000=2^45^3 and phi(2000)=800=2^55^2 so 2000 is in the sequence.`
	CROSSREFS	`Cf. A110751, A110819, A027598, A081377.` `Sequence in context: A161994 A070738 A055744 this_sequence A033310 A104235 A143718` `Adjacent sequences: A141715 A141716 A141717 this_sequence A141719 A141720 A141721`
	KEYWORD	`easy,nonn`
	AUTHOR	`Farideh Firoozbakht (mymontain(AT)yahoo.com), Jul 01 2008`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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