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A036452
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a(n) = d(d(d(d(n)))), the 4th iterate of number-of-divisors function with initial value of n.
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11
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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, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2
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OFFSET
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1,2
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COMMENTS
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The iterated d function rapidly converges to fixed point 2. For k=4, the first n for which a(n)>2 is 60.
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LINKS
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FORMULA
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a(n) = d(d(d(d(n)))).
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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 4th term is a(96)=3.
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MATHEMATICA
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PROG
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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