Euler's totient function φ(n) counts the number of positive integers less than n that are relatively prime to n. For example, φ(10) = 4, as there are four positive integers less than 10 that are relatively prime to 10: 1, 3, 7, and 9.
Euler's totient function φ(n) counts the number of positive integers less than n that are relatively prime to n. For example, φ(10) = 4, as there are four positive integers less than 10 that are relatively prime to 10: 1, 3, 7, and 9.