id:A066763 - OEIS Search Results

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Numbers n such that (n,EulerPhi(n)) lies on a circle with integral radius centered at the origin, i.e. n^2 + EulerPhi[n]^2 is a square.

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15, 45, 70, 75, 135, 140, 225, 280, 350, 375, 377, 405, 490, 560, 627, 665, 675, 700, 980, 1120, 1125, 1215, 1400, 1750, 1875, 1881, 1960, 2025, 2240, 2450, 2800, 3325, 3375, 3430, 3500, 3645, 3655, 3920, 4480, 4655, 4900, 4901, 5600, 5625, 5643, 6075 (list; graph; listen)

	OFFSET	`1,1`
	EXAMPLE	`15^2 + EulerPhi[15]^2 = 225 + 64 = 289 = 17^2; so 15 is a term of the sequence.`
	MATHEMATICA	`Select[ Range[ 1, 10^4 ], IntegerQ[ Sqrt[ #^2 + EulerPhi[ # ]^2 ] ] & ]`
	CROSSREFS	`Sequence in context: A029827 A119123 A084821 this_sequence A033849 A060536 A014634` `Adjacent sequences: A066760 A066761 A066762 this_sequence A066764 A066765 A066766`
	KEYWORD	`nonn`
	AUTHOR	`Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Jan 17 2002`

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Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.

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