MathDB
99% fine numbers

Source: Poland 2014 - Second Round P6

July 28, 2019
number theoryprime numbers

Problem Statement

Call a positive number nn fine, if there exists a prime number pp such that pnp|n and p2np^2\nmid n. Prove that at least 99% of numbers 1,2,3,,10121, 2, 3, \ldots, 10^{12} are fine numbers.