id:A071575 - OEIS Search Results

Search: id:A071575

Displaying 1-1 of 1 results found.

page 1

Number of iterations of cototient(n) needed to reach 1 (cototient(x) = x-phi(x)).

+0
1

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; listen)

	OFFSET	`1,4`
	COMMENT	`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`
	PROGRAM	`(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: A029231 A025808 A144079 this_sequence A038569 A020650 A124224` `Adjacent sequences: A071572 A071573 A071574 this_sequence A071576 A071577 A071578`
	KEYWORD	`easy,nonn`
	AUTHOR	`Benoit Cloitre (benoit7848c(AT)orange.fr), May 31 2002`
	EXTENSIONS	`Prepended a(1)=0 and changed offset. - T. D. Noe (noe(AT)sspectra.com), Dec 03 2008`

page 1

Search completed in 0.002 seconds

Last modified December 17 23:40 EST 2009. Contains 171025 sequences.

AT&T Labs Research