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A126602
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a(1)=2^3*5*7*29=8120; for n>1, a(n) = (-1)sigma(a(n-1)).
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1
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8120, 8736, 8784, 19140, 11200, 21750, 8624, 15950, 8120, 8736, 8784, 19140, 11200, 21750, 8624, 15950, 8120, 8736, 8784, 19140, 11200, 21750, 8624, 15950, 8120, 8736, 8784, 19140, 11200, 21750, 8624, 15950, 8120, 8736, 8784, 19140
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OFFSET
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1,1
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COMMENTS
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(-1)sigma is defined in A049060. This is a cyclic sequence whose period is 8, so these numbers are called "(-1)sigma sociable numbers of order 8".
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LINKS
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Table of n, a(n) for n=1..36.
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EXAMPLE
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The numbers are 2^3*5*7*29, 2^5*3*7*13, 2^4*3^2*61, 2^2*3*5*11*29, 2^6*5^2*7, 2*3*5^3*29, 2^4*7^2*11, 2*5^2*11*29, then repeat.
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CROSSREFS
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Sequence in context: A163045 A069368 A068758 * A209845 A025288 A025306
Adjacent sequences: A126599 A126600 A126601 * A126603 A126604 A126605
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane, Feb 14 2008, based on a posting to the Sequence Fans Mailing List by Yasutoshi Kohmoto (zbi74583(AT)boat.zero.ad.jp), Feb 02 2005
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STATUS
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approved
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