Metamath Proof Explorer

Theorem 4nprm

Description: 4 is not a prime number. (Contributed by Paul Chapman, 22-Jun-2011) (Proof shortened by Mario Carneiro, 18-Feb-2014)

Ref Expression
Assertion 4nprm 
|- -. 4 e. Prime

Proof

Step Hyp Ref Expression
1 2nn 
 |-  2 e. NN
2 1lt2 
 |-  1 < 2
3 2t2e4 
 |-  ( 2 x. 2 ) = 4
4 1 1 2 2 3 nprmi 
 |-  -. 4 e. Prime