MathDB
Prove that M =ℤ+ [ILL 1974]

Source:

January 2, 2011
floor functionalgebra proposedalgebra

Problem Statement

Let MM be a nonempty subset of Z+\mathbb Z^+ such that for every element xx in M,M, the numbers 4x4x and ⌊x⌋\lfloor \sqrt x \rfloor also belong to M.M. Prove that M=Z+.M = \mathbb Z^+.
Back to ProblemsView on AoPS