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A019290
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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 (2,13)-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: A145685 A138597 A206758 * A069335 A166195 A031861
Adjacent sequences: A019287 A019288 A019289 * A019291 A019292 A019293
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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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