=+

(e) Euler's function (n) is the number of positive integers less than n and relatively prime to it. Let p1 ,..., p, be the distinct prime factors of n; from the inclusion-exclusion formula for the events [m: p; Im], (2.36), and the fact that the p, divide n, deduce 4(n)

- п(1-1).

(2.37)

n pln