here for two solutions.
Prove that for ANY integer n, has no prime divisors of the form 6m-1.
Let p be a prime divisor of .
Then ≡ 0 (mod p)
=> ≡ 0 (mod p)
=> ≡ 1 (mod p)
Let = order of n mod p
=> = 1 or 3
Now I'm stuck here. How to finish the proof from here?
Any help is greatly appreciated!
[also under discussion in math links forum]