A218427 - OEIS

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A218427

Numbers k for which sigma(k)/k - 4/5 is an integer.

10, 60, 1170, 114660, 72602880, 668304000, 714954240, 1307124000, 1381161600, 2701389600, 8052817920, 10181689600, 643773312000, 1330464844800, 2015156183040, 3522876144480, 15462510336000, 23885971200000, 702577007193600, 908714417345280 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,1`
	COMMENTS	`a(13) > 10^11. - Donovan Johnson, Oct 31 2012` `a(14) > 10^12. - Giovanni Resta, Nov 04 2012`
	LINKS	`Table of n, a(n) for n=1..20.` `M. Drennen, T. Gunter, P. Johnson and J. Ward, The Loneliest Number` `Jeffrey Ward, Does Ten Have a Friend?, arXiv:0806.1001 [math.NT], 2008.`
	CROSSREFS	`Cf. A218406, A218407, A218408.` `Sequence in context: A219368 A052664 A090373 * A354944 A041184 A089034` `Adjacent sequences: A218424 A218425 A218426 * A218428 A218429 A218430`
	KEYWORD	`nonn`
	AUTHOR	`Zdenek Cervenka, Oct 28 2012`
	EXTENSIONS	`a(5)-a(12) from Donovan Johnson, Oct 31 2012` `a(13) from Giovanni Resta, Nov 04 2012` `More terms from Michel Marcus, Jun 26 2013`
	STATUS	`approved`

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Last modified May 21 11:30 EDT 2024. Contains 372736 sequences. (Running on oeis4.)