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A019286
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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.
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OFFSET
| 1,1
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COMMENTS
| See also the Cohen-te Reile links under A019276.
No other terms < 5x10^11. - Jud McCranie, Feb 08 2012
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REFERENCES
| Graeme L. Cohen and Herman J. J. te Riele, Iterating the sum-of-divisors function, Experimental Mathematics, 5 (1996), pp. 93-100.
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LINKS
| Experimental Mathematics, Home Page
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CROSSREFS
| Sequence in context: A011785 A003800 A006363 * A064767 A115222 A035827
Adjacent sequences: A019283 A019284 A019285 * A019287 A019288 A019289
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KEYWORD
| nonn,changed
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| a(8) by Jud McCranie, Jan 28 2012
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