MathDB
Function number theory

Source: Iran second round 2016,day2,problem6

April 29, 2016
functionnumber theory

Problem Statement

Find all functions f:NNf: \mathbb N \to \mathbb N Such that: 1.for all x,yNx,y\in N:x+yf(x)+f(y)x+y|f(x)+f(y) 2.for all x1395x\geq 1395:x32f(x)x^3\geq 2f(x)