id:A129827 - OEIS Search Results

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Numbers n such that Euler's totient phi(n) divided by 2 is a perfect square.

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3, 4, 6, 15, 16, 19, 20, 24, 27, 30, 38, 51, 54, 64, 68, 73, 80, 91, 95, 96, 102, 111, 117, 120, 135, 146, 148, 152, 163, 182, 190, 216, 222, 228, 234, 243, 252, 255, 256, 270, 272, 275, 303, 320, 323, 326, 340, 365, 375, 384, 404, 408, 455, 459, 480, 486, 500 (list; graph; listen)

	OFFSET	`1,1`
	LINKS	`Walter Nissen, Home Page (listed in lieu of email address)`
	EXAMPLE	`a(4) is 15 because phi ( 15 ) = 8, which is twice the square of 2 .`
	CROSSREFS	`Cf. A000010, A000290.` `Sequence in context: A137820 A049892 A063477 this_sequence A122727 A089249 A092933` `Adjacent sequences: A129824 A129825 A129826 this_sequence A129828 A129829 A129830`
	KEYWORD	`nonn`
	AUTHOR	`Walter Nissen May 20 2007`

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Last modified December 7 08:40 EST 2009. Contains 170430 sequences.

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