A019286 - OEIS

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A019286

Let sigma_m (n) be result of applying sum-of-divisors function m times to n; call n (m,k)-perfect if sigma_m (n) = k*n; sequence gives the (2,9)-perfect numbers.

168, 10752, 331520, 691200, 1556480, 1612800, 106151936, 5099962368 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,1`
	COMMENTS	`See also the Cohen-te Reile links under A019276.` `No other terms < 5x10^11. - Jud McCranie, Feb 08 2012`
	REFERENCES	`Graeme L. Cohen and Herman J. J. te Riele, Iterating the sum-of-divisors function, Experimental Mathematics, 5 (1996), pp. 93-100.`
	LINKS	`Table of n, a(n) for n=1..8.` `Experimental Mathematics, Home Page`
	CROSSREFS	`Sequence in context: A011785 A003800 A006363 * A218413 A064767 A115222` `Adjacent sequences: A019283 A019284 A019285 * A019287 A019288 A019289`
	KEYWORD	`nonn`
	AUTHOR	`N. J. A. Sloane.`
	EXTENSIONS	`a(8) by Jud McCranie, Jan 28 2012`
	STATUS	`approved`

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Last modified May 22 03:34 EDT 2013. Contains 225511 sequences.