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A019293

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 (4,k)-perfect numbers.

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1, 2, 3, 4, 6, 8, 10, 12, 15, 18, 21, 24, 26, 32, 39, 42, 60, 65, 72, 84, 96, 160, 182, 336, 455, 512, 896, 960, 992, 1023, 1280, 1536, 1848, 2040, 2688, 4092, 5920, 7808, 7936, 10416, 16352, 20384, 21824, 23424, 24564, 29127, 33792, 41440 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`See also the Cohen-te Reile links under A019276.`
	REFERENCES	`Graeme L. Cohen and Herman J. J. te Riele, Iterating the sum-of-divisors function, Experimental Mathematics, 5 (1996), pp. 93-100.`
	LINKS	`Experimental Mathematics, Home Page`
	CROSSREFS	`Sequence in context: A062418 A056168 A054041 this_sequence A130519 A001972 A005705` `Adjacent sequences: A019290 A019291 A019292 this_sequence A019294 A019295 A019296`
	KEYWORD	`nonn`
	AUTHOR	`N. J. A. Sloane (njas(AT)research.att.com).`

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Last modified December 5 23:38 EST 2009. Contains 170428 sequences.

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