MathDB
A subset of (1, 2, ..., n)

Source: China TST 2007, Problem 6

December 29, 2008
least common multiplenumber theoryrelatively primenumber theory unsolved

Problem Statement

Let n n be a positive integer, let A A be a subset of {1,2,⋯ ,n} \{1, 2, \cdots, n\}, satisfying for any two numbers x,y∈A x, y\in A, the least common multiple of x x, y y not more than n n. Show that |A|\leq 1.9\sqrt {n} \plus{} 5.
Back to ProblemsView on AoPS