MathDB

4

Part of 2002 Balkan MO

Problems(1)

Integer functions fulfilling a double inequality

Source: Balkan MO 2002, problem 4

4/24/2006
Determine all functions f:N→Nf: \mathbb N\to \mathbb N such that for every positive integer nn we have: 2n+2001≤f(f(n))+f(n)≤2n+2002. 2n+2001\leq f(f(n))+f(n)\leq 2n+2002.
functioninequalitiesalgebra proposedalgebra