Hi evebody,

Is there any proof of:

Let$\displaystyle P_1, P_2$ two different primes

Prove (or plz give me a link) that if

$\displaystyle

a=P_1^s-P_2^s

$

then

$\displaystyle

a \quad mod \quad P_1 \quad /= 0

$

$\displaystyle

a \quad mod \quad P_2 \quad /= 0

$

For every positive integer s

(/= means not equal)

Thank you a lot