id:A166069 - OEIS Search Results

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Multiply perfect numbers k such that sigma(k)/k > 2.

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120, 672, 30240, 32760, 523776, 2178540, 23569920, 45532800, 142990848, 459818240, 1379454720, 1476304896, 14182439040, 31998395520, 43861478400, 51001180160, 66433720320, 153003540480, 403031236608, 518666803200 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`Subsequence of multiply perfect numbers (A007691). Numbers k = A007691(n) such that sigma(A007691(n))/A007691(n) > 2. Numbers k = A007691(n) such that A054030(n) > 2.`
	LINKS	`Charles R Greathouse IV, Table of n, a(n) for n=1..1587`
	EXAMPLE	`For n = 1 the a(1) = 120, sigma(120) / 120 = 360 / 120 = 3, i.e. > 2.`
	CROSSREFS	`Sequence in context: A100145 A090216 A113546 this_sequence A114887 A069085 A039688` `Adjacent sequences: A166066 A166067 A166068 this_sequence A166070 A166071 A166072`
	KEYWORD	`nonn`
	AUTHOR	`Jaroslav Krizek (jaroslav.krizek(AT)atlas.cz), Oct 06 2009`
	EXTENSIONS	`Extended by Charles R Greathouse IV (charles.greathouse(AT)case.edu), Oct 12 2009`

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

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