MathDB

4.

Let

N

be an integer greater than

1

.Denote by

x

the smallest positive integer with the following property:there exists a positive integer

y

strictly less than

x-1

, such that

x

divides

N+y

.Prove that x is either

p^n

2p

, where

p

is a prime number and

n

is a positive integer

4