Euler Totient, Revised

Define Φ ( N ) \Phi(N) to be Euler's totient function, which is the number of positive integers x x in 0 < x < N 0<x<N S.T. G C D ( x , N ) = 1 GCD(x,N)=1 . How many positive integers, in 1 y 1 0 3 1\leq y \leq 10^{3} , are not divisible by 2 2 and satisfy the following?

Φ ( Φ ( y ) ) = 2 t , t { 1 , 2 , 3 , } \Phi \left(\Phi \left(y\right)\right)=2^t \ , \ t \in \{1,2,3,\dots\}


The answer is 86.

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1 solution

Scrub Lord
Jan 6, 2019

This problem is begging to be solved with a computer. Here's my C script.

You scrubbed it so well, it is bleeding :) I do not think I came up with an analytical solution myself. So, thanks for sharing your script.

A Former Brilliant Member - 2 years, 5 months ago

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Thank you :)

Scrub Lord - 2 years, 5 months ago

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