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A071575
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Number of iterations of cototient(n) needed to reach 1 (cototient(x) = x-phi(x)).
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1
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0, 1, 1, 2, 1, 3, 1, 3, 2, 4, 1, 4, 1, 4, 2, 4, 1, 5, 1, 5, 3, 5, 1, 5, 2, 5, 3, 5, 1, 6, 1, 5, 2, 6, 2, 6, 1, 6, 3, 6, 1, 7, 1, 6, 4, 6, 1, 6, 2, 7, 2, 6, 1, 7, 3, 6, 4, 7, 1, 7, 1, 6, 4, 6, 2, 7, 1, 7, 3, 7, 1, 7, 1, 7, 3, 7, 2, 8, 1, 7, 4, 8, 1, 8, 4, 7, 2, 7, 1, 8, 2, 7, 3, 7, 2, 7, 1, 7, 4, 8, 1, 8, 1, 7, 5, 8
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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COMMENTS
| Equals A076640(n)-1.
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LINKS
| T. D. Noe, Table of n, a(n) for n=1..10000
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FORMULA
| a(n) = a(n-phi(n))+1, a(1) = 0.
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EXAMPLE
| cototient(6) = 4 cototient(4) = 2 cototient(2) = 1 hence a(6) = 3
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PROG
| (PARI) for(n=1, 150, s=n; t=0; while(s!=1, t++; s=s-eulerphi(s); if(s==1, print1(t, ", "); ); ))
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CROSSREFS
| Cf. A032358.
Sequence in context: A029231 A025808 A144079 * A038569 A020650 A124224
Adjacent sequences: A071572 A071573 A071574 * A071576 A071577 A071578
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KEYWORD
| easy,nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), May 31 2002
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EXTENSIONS
| Prepended a(1)=0 and changed offset. - T. D. Noe (noe(AT)sspectra.com), Dec 03 2008
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