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A075701
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a(1)=1, a(n+1)=sigma(a(n))-2*a(n).
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0
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1, -1, 3, -2, 7, -6, 24, 12, 4, -1, 3, -2, 7, -6, 24, 12, 4, -1, 3, -2, 7, -6, 24, 12, 4, -1, 3, -2, 7, -6, 24, 12, 4, -1, 3, -2, 7, -6, 24, 12, 4, -1, 3, -2, 7, -6, 24, 12, 4, -1, 3, -2, 7, -6, 24, 12, 4, -1, 3, -2, 7, -6, 24, 12, 4, -1, 3, -2, 7, -6, 24, 12, 4, -1, 3, -2, 7, -6, 24, 12, 4, -1, 3, -2, 7, -6, 24, 12, 4, -1, 3, -2, 7, -6
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| Taking any nonperfect number as initial value, does the map x->sigma(x)-2x lead to the cycle (-1,3,-2,7,-6,24,12,4) if during the iteration no perfect number is reached? Example: 124 -> -24 -> 108 -> 64 -> -1 -> 3 -> -2 -> 7 -> -6 -> 24 -> 12 -> 4 and the cycle (-1,3,-2,7,-6,24,12,4) is reached.
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FORMULA
| Periodic with period (-1, 3, -2, 7, -6, 24, 12, 4) of length 8.
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CROSSREFS
| Sequence in context: A082824 A088657 A005213 * A016603 A199183 A178908
Adjacent sequences: A075698 A075699 A075700 * A075702 A075703 A075704
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KEYWORD
| sign
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), Oct 02 2002
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