id:A116004 - OEIS Search Results

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Numbers n such that n*sigma(n)*sigma(sigma(n)) is a square.

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1, 42, 234, 2430, 3510, 3724, 6750, 49005, 72618, 165726, 167580, 318091, 412776, 510489, 642096, 771875, 816998, 859740, 1003275, 1073452, 1166719, 1368576, 1604645, 1712256, 1984500, 2297762, 2500875, 2735810, 2852928, 3082950 (list; graph; listen)

	OFFSET	`1,2`
	EXAMPLE	`234sigma(234)sigma(sigma(234))=13104^2.`
	CROSSREFS	`Cf. A116005.` `Adjacent sequences: A116001 A116002 A116003 this_sequence A116005 A116006 A116007` `Sequence in context: A090198 A008446 A122232 this_sequence A122242 A046655 A064369`
	KEYWORD	`nonn`
	AUTHOR	`Giovanni Resta (g.resta(AT)iit.cnr.it), Feb 13 2006`

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Last modified October 12 15:26 EDT 2008. Contains 144830 sequences.

AT&T Labs Research