MathDB
2020 Canadian MO P4

Source:

March 14, 2020
number theoryCanada

Problem Statement

S={1,4,8,9,16,...}S= \{1,4,8,9,16,...\} is the set of perfect integer power. ( S={nkn,kZ,k2}S=\{ n^k| n, k \in Z, k \ge 2 \}. )We arrange the elements in SS into an increasing sequence {ai}\{a_i\} . Show that there are infinite many nn, such that 9999an+1an9999|a_{n+1}-a_n