MathDB
Perfect cube

Source: Turkey National Olympiad Second Round 2013 P2

November 28, 2013

Problem Statement

Let mm be a positive integer. a. Show that there exist infinitely many positive integers kk such that 1+km31+km^3 is a perfect cube and 1+kn31+kn^3 is not a perfect cube for all positive integers n<mn<m. b. Let m=prm=p^r where p2(mod3)p \equiv 2 \pmod 3 is a prime number and rr is a positive integer. Find all numbers kk satisfying the condition in part a.