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A054740
Cototient(n)/totient(n) when this is an integer.
1
0, 1, 1, 2, 1, 2, 1, 2, 2, 1, 2, 2, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2
OFFSET
1,4
COMMENTS
EulerPhi of x divides x (A007694) if and only if EulerPhi divides x-EulerPhi. This quotient is smaller by 1 than A049237.
REFERENCES
Sárközy A. and Suranyi J., Number Theory Problem Book (in Hungarian)
FORMULA
EXAMPLE
x=2592, Phi[2592]=864, Cototient[x]=2592-864=1728 and the quotients are as follows: x/Phi=2592/864=3 or Cototient[x]/Phi[x]=1728/864=2; x always has a form of 2^u*3^w
MATHEMATICA
Select[(#-EulerPhi[#])/EulerPhi[#]&/@Range[300000], IntegerQ] (* Harvey P. Dale, Mar 01 2015 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Apr 26 2000
STATUS
approved