id:A128853 - OEIS Search Results

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a(n) = the number of positive divisors of n which are coprime to phi(n) = A000010(n).

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1, 2, 2, 1, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 4, 1, 2, 1, 2, 2, 2, 2, 2, 2, 1, 2, 1, 2, 2, 4, 2, 1, 4, 2, 4, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 4, 2, 2, 1, 2, 2, 2, 2, 2, 4, 2, 2, 2, 1, 4, 4, 2, 2, 4, 4, 2, 1, 2, 2, 2, 2, 4, 2, 2, 2, 1, 2, 2, 2, 4, 2, 4, 2, 2, 2, 4, 2, 2, 2, 4, 2, 2, 1, 2, 1, 2, 4, 2, 2, 4 (list; graph; listen)

	OFFSET	`1,2`
	LINKS	`Leroy Quet, Home Page (listed in lieu of email address)`
	EXAMPLE	`12 is coprime to 4 positive integers (1,5,7 and 11) which are <= 12; so phi(12)=4. There are 2 divisors (1 and 3) of 12 that are coprime to 4. So a(12) = 2.`
	MAPLE	`with(numtheory): a:=proc(n) local div, ct, j: div:=divisors(n): ct:=0: for j from 1 to tau(n) do if igcd(div[j], phi(n))=1 then ct:=ct+1 else fi od: ct; end: seq(a(n), n=1..140); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 17 2007`
	CROSSREFS	`Sequence in context: A023671 A117535 A072463 this_sequence A136165 A134193 A085030` `Adjacent sequences: A128850 A128851 A128852 this_sequence A128854 A128855 A128856`
	KEYWORD	`nonn`
	AUTHOR	`Leroy Quet Apr 16 2007`
	EXTENSIONS	`More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 17 2007`

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Last modified March 20 09:10 EDT 2010. Contains 173642 sequences.

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