Odredi sve funkcije f:N0→N0f: \mathbb{N}_0 \to \mathbb{N}_0f:N0→N0 takve da za sve x∈N0x \in \mathbb{N}_0x∈N0, y∈Ny \in \mathbb{N}y∈N vrijedi: (f(x)+1)(f(y)+1)=(x+1)(f(y−1)+1)+f(x+1).(f(x) + 1)(f(y) + 1) = (x + 1)(f(y - 1) + 1) + f(x + 1).(f(x)+1)(f(y)+1)=(x+1)(f(y−1)+1)+f(x+1).