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A019282
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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 (2,4)-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 < 5 x 10^11. - 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: A067408 A102102 A196569 * A082158 A064625 A205602
Adjacent sequences: A019279 A019280 A019281 * A019283 A019284 A019285
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KEYWORD
| nonn,bref,changed
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| a(4) by Jud McCranie, Feb 08 2012
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