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Search: id:A036453
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| A036453 |
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a(n)=d[ d[ d[ d[ d[ n ] ] ] ] ], the 5th iterate of number-of-divisors function with initial value of n. |
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+0
8
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| 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2
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OFFSET
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1,2
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COMMENT
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The iterated d function rapidly converges to fixed point 2. In the 5-th iterated d-sequence the first term different from the fixed point 2 appears at n=5040. The 6th and further iterated sequences have very long initial segment of 2's. In the 6th one the first non-stationary term is a(293318625600)=3. In such sequences any large value occurs infinite many times and constructible.
Differs from A007395 for n=1, 5040, 7920, 8400, 9360, 10080, 10800 etc. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 20 2008]
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FORMULA
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a[ n ]=Nest[ d, n, 5 ]
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EXAMPLE
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E.g. n=96 and its successive iterates are 12,6,4,3 and 2. The 5th term is a(96)=2 is stationary(fixed).
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CROSSREFS
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A000005, A015553, A036450, A036452.
Sequence in context: A084100 A130130 A046698 this_sequence A040000 A007395 A055642
Adjacent sequences: A036450 A036451 A036452 this_sequence A036454 A036455 A036456
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu)
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