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 A071575 Number of iterations of cototient(n) needed to reach 1 (cototient(x) = x-phi(x)). 2
 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; text; internal format)
 OFFSET 1,4 COMMENTS Equals A076640(n)-1. LINKS T. D. Noe, Table of n, a(n) for n=1..10000 FORMULA a(n) = a(n-phi(n))+1, a(1) = 0. EXAMPLE cototient(6) = 4 cototient(4) = 2 cototient(2) = 1 hence a(6) = 3 PROG (PARI) for(n=1, 150, s=n; t=0; while(s!=1, t++; s=s-eulerphi(s); if(s==1, print1(t, ", "); ); )) CROSSREFS Cf. A032358. Sequence in context: A025808 A144079 A326839 * A307908 A316436 A303674 Adjacent sequences:  A071572 A071573 A071574 * A071576 A071577 A071578 KEYWORD easy,nonn AUTHOR Benoit Cloitre, May 31 2002 EXTENSIONS Prepended a(1)=0 and changed offset. - T. D. Noe, Dec 03 2008 STATUS approved

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Last modified August 4 08:25 EDT 2020. Contains 336201 sequences. (Running on oeis4.)