I would like to solve this problem: What is the smallest positive integer that can be expressed as the sum a^3 + b^3 and which can also be expressed as the sum c^3 + d^3, if a,b,c, and d are distinct positive integers? I can't get mathematica to find this answer, or even to find a and b so a^2 + b^2 = 25 and a and b are natural numbers. I have mathematica 4.0 for students, which is basically identical to professional version. Please help me out! Thanks.