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A049115
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Repeatedly apply Euler phi to n; a(n) = number of iterations that are applied to numbers that are not powers of 2.
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2
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0, 0, 1, 0, 1, 1, 2, 0, 2, 1, 2, 1, 2, 2, 1, 0, 1, 2, 3, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 1, 2, 0, 2, 1, 2, 2, 3, 3, 2, 1, 2, 2, 3, 2, 2, 3, 4, 1, 3, 2, 1, 2, 3, 3, 2, 2, 3, 3, 4, 1, 2, 2, 3, 0, 2, 2, 3, 1, 3, 2, 3, 2, 3, 3, 2, 3, 2, 2, 3, 1, 4, 2, 3, 2, 1, 3, 3, 2, 3, 2, 3, 3, 2, 4, 3, 1, 2, 3, 2, 2, 3, 1, 2, 2, 2
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OFFSET
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1,7
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..10000
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FORMULA
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The smallest x so that Nest[ EulerPhi, n, x ] = 2^w is just achieved.
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EXAMPLE
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If n is a power of 2, then a(n)=0 by definition. If n=59049, then {59049,39366,13122,4374,1458,486,54,18,6,2,1}. This phi-sequence has a length of 12 and includes 10 non-2-powers, so a(59049)=8.
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CROSSREFS
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A000010.
Sequence in context: A039701 A025822 A051585 * A029367 A192541 A099302
Adjacent sequences: A049112 A049113 A049114 * A049116 A049117 A049118
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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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STATUS
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approved
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