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Search: id:A093863
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| A093863 |
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Unitary sigma-unitary phi super perfect numbers: USUP(USUP(n))=1/k*n for some integer k. |
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+0
1
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| 1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 16, 17, 18, 20, 24, 34, 36, 40, 48, 68, 72, 80
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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If n=Product p_i^r_i then USUP(n)= UnitarySigma(2^r_1)*UnitaryPhi(n/2^r_1) =(2^r_1+1)*Product(p_i^r_i-1), 2<p_i k values of these terms are all 1, so they are fixed points of the function : USUP(USUP(n)). k values which are more than 1 exist, for example USUP(USUP(4320))= (1/2) *4320.
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EXAMPLE
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USUP(2^4*7^2)=UnitarySigma(2^4)*UnitaryPhi(7^2)=17*48= 816
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CROSSREFS
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Cf. A092760.
Sequence in context: A061945 A029509 A048645 this_sequence A091902 A067698 A110495
Adjacent sequences: A093860 A093861 A093862 this_sequence A093864 A093865 A093866
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KEYWORD
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nonn
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AUTHOR
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Yasutoshi Kohmoto (zbi74583(AT)boat.zero.ad.jp), May 11 2004
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