Suppose and that is not a prime, then may be:
1 - comprised of 2 distinct prime factors
2 - comprised of 3 distinct prime factors
3 - comprised of at least 4 distinct prime factors
Submit your answer as the sum of the squares of the numbers corresponding to the statements which are true, e.g. if statements 2 and 3 are correct then submit the answer as
denotes the Euler-Totient Function
Inspired by George E. Andrews Number Theory
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This solution is based on the assumption that such a composite n exists.
1- Obviously n = p k ∗ m , where k ≥ 2 and p is a prime and G C D ( p , m ) = 1 . Otherwise p ∣ ϕ ( n ) and we know that p ∤ n − 1 . Therefore, n is a square free composite.
2- If n = p q , where p and q are distinct primes, then
( p − 1 ) ( q − 1 ) ∣ p q − 1 ⟹ p − 1 ∣ q − 1 , q − 1 ∣ p − 1 ⟹ p = q
which suggests that p and q are not distinct.
3- If n = p q r , where p , q and r are distinct primes and p > q > r , then, we need 2 ϕ ( n ) ≤ n and it would be possibly achieved, when p , q , r are as small as possible.
ϕ ( n ) = ( p − 1 ) ( q − 1 ) ( r − 1 ) > ( p − 1 ) . 4 . 2 = 8 ( p − 1 ) ⟹ 2 . 8 ( p − 1 ) = 1 6 ( p − 1 ) > 3 . 5 . ( p ) − 1 = 1 5 p − 1 ⟹ p < 1 6
one can check all the possible p , q , r < 1 6 to realise they won't satisfy the requirement.
4- Note that we need
∏ j = 1 k ( p j − 1 ) ∏ j = 1 k p j ≥ 2 ⟹ j = 1 ∑ k lo g ( p j ) − j = 1 ∑ k lo g ( p j − 1 ) ≈ j = 1 ∑ k p j 1 ≥ lo g 2
for some k ∈ N .
∑ j = 1 k p j 1 is a divergent sum, hence, ∏ j = 1 k ( p j − 1 ) ∏ j = 1 k p j ≥ 2 would be satisfied for some k ∈ N .