id:A067811 - OEIS Search Results

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Numbers n such that phi(n)^2 + sigma(n)^2 is an integer square.

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7, 32, 33, 41, 68, 145, 209, 237, 239, 266, 328, 372, 384, 385, 442, 522, 622, 905, 945, 1157, 1243, 1288, 1357, 1581, 1615, 1643, 1798, 1853, 1885, 1978, 1995, 2093, 2418, 2541, 2698, 2765, 2769, 2981, 3013, 3161, 3315, 3451, 3519, 3577, 4041, 4309, 4318 (list; graph; listen)

	OFFSET	`1,1`
	EXAMPLE	`phi(32)^2 + sigma(32)^2 = 16^2 + 63^2 = 4225 = 65^2, so 32 is a term of the sequence.`
	MATHEMATICA	`Select[Range[10^4], IntegerQ[Sqrt[EulerPhi[ # ]^2 + DivisorSigma[1, # ]^2]] &]`
	CROSSREFS	`Adjacent sequences: A067808 A067809 A067810 this_sequence A067812 A067813 A067814` `Sequence in context: A134709 A139314 A101329 this_sequence A044084 A044465 A029484`
	KEYWORD	`easy,nonn`
	AUTHOR	`Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Feb 07 2002`

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Last modified October 13 20:18 EDT 2008. Contains 145016 sequences.

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