2

Part of 2021 Canadian Junior Mathematical Olympiad

Problems(1)

first k elements of permutation of first n have distinct remainder mod k

Source: Canadian Junior Mathematical Olympiad - CJMO 2021 p2

How many ways are there to permute the first

n

positive integers such that in the permutation, for each value of

k \le n

k

elements of the permutation have distinct remainder mod

k

remaindernumber theory