Let ϕ be the Euler's function and fix an integer k ≥ 0. We show that, for every initial value x 1 ≥ 1, the sequence of positive integers (xn) n≥1 defined by x n+1 = ϕ(xn) + k for all n ≥ 1 is eventually periodic. Similarly, for every initial value x 1 , x 2 ≥ 1, the sequence of positive integers (xn) n≥1 defined by x n+2 = ϕ(x n+1 )+ϕ(xn)+k for all n ≥ 1 is eventually periodic, provided that k is even.