A054740 Cototient(n)/totient(n) when this is an integer.

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)

Links

Table of n, a(n) for n=1..105.

Formula

A051953[A007694(n)]/A000010[A007694(n)] = A049237(n)-1

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

A000010, A049237, A007694, A051953.

Sequence in context: A212179 A257023 A238894 * A272947 A177740 A118458

Adjacent sequences: A054737 A054738 A054739 * A054741 A054742 A054743

Keyword

nonn

Author

Labos Elemer, Apr 26 2000

Status

approved