phi(n) divides n-1 implies n is prime

Prove that if then is prime, where . is the Euler's totient function.

I am able to show that is square-free under the above condition.

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Originally Posted by abhishekkgp

Prove that if then is prime, where . is the Euler's totient function.

I am able to show that is square-free under the above condition.

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Lehmer's conjecture

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Originally Posted by princeps

Lehmer's conjecture

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Thank You. I did not know its an unsolved problem or I would not post it.