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A097946 a(n) = A008683(n)*A014197(n) where A008683 is the Moebius (or Mobius) function mu(n) and A014197 is the number of numbers m with Euler phi(m) = n. 3

%I #7 Jul 19 2017 20:07:57

%S 2,-3,0,0,0,4,0,0,0,2,0,0,0,0,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,-2,0,0,0,

%T 0,0,0,0,0,0,0,0,-4,0,0,0,2,0,0,0,0,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,-2,

%U 0,0,0,-2,0,0,0,0,0,0,0,-2,0,0,0,2,0,0,0,0,0,0,0,0,0,0

%N a(n) = A008683(n)*A014197(n) where A008683 is the Moebius (or Mobius) function mu(n) and A014197 is the number of numbers m with Euler phi(m) = n.

%C For n < 93 and a(n) not 0, n = p - 1 where p is prime and therefore in A077064 (Squarefree numbers of form prime - 1.)

%H Antti Karttunen, <a href="/A097946/b097946.txt">Table of n, a(n) for n = 1..10000</a>

%o (PARI)

%o A014197(n, m=1) = { n==1 && return(1+(m<2)); my(p, q); sumdiv(n, d, if( d>=m && isprime(d+1), sum( i=0, valuation(q=n\d, p=d+1), A014197(q\p^i, p))))} \\ This function from _M. F. Hasler_, Oct 05 2009

%o A097946(n) = moebius(n)*A014197(n); \\ _Antti Karttunen_, Jul 19 2017

%Y Cf. A000010, A008683, A014197, A077064, A097945.

%K sign

%O 1,1

%A _Gerald McGarvey_, Sep 04 2004

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Last modified May 16 11:24 EDT 2024. Contains 372552 sequences. (Running on oeis4.)