How to prove:

[DRA1998]

for all n>1:
?|4((? − 1)! + 1)
to prove: n = 4 OR n is prime
Any help or guidance would be appreciated

 

[Dr.Peterson]

for all n>1:
?|4((? − 1)! + 1)
to prove: n = 4 OR n is prime
Any help or guidance would be appreciated

Please check whether you've quoted the problem correctly. I don't think it makes sense to state something about all n, then ask to prove that n must be only certain numbers.