| Step | Hyp | Ref | Expression | 
						
							| 1 |  | simp2 | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝑀  ∈  ℕ0  ∧  𝑀  <  𝑁 )  →  𝑀  ∈  ℕ0 ) | 
						
							| 2 |  | nn0z | ⊢ ( 𝑀  ∈  ℕ0  →  𝑀  ∈  ℤ ) | 
						
							| 3 |  | nn0z | ⊢ ( 𝑁  ∈  ℕ0  →  𝑁  ∈  ℤ ) | 
						
							| 4 |  | znnsub | ⊢ ( ( 𝑀  ∈  ℤ  ∧  𝑁  ∈  ℤ )  →  ( 𝑀  <  𝑁  ↔  ( 𝑁  −  𝑀 )  ∈  ℕ ) ) | 
						
							| 5 | 2 3 4 | syl2anr | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝑀  ∈  ℕ0 )  →  ( 𝑀  <  𝑁  ↔  ( 𝑁  −  𝑀 )  ∈  ℕ ) ) | 
						
							| 6 | 5 | biimp3a | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝑀  ∈  ℕ0  ∧  𝑀  <  𝑁 )  →  ( 𝑁  −  𝑀 )  ∈  ℕ ) | 
						
							| 7 |  | fmtnodvds | ⊢ ( ( 𝑀  ∈  ℕ0  ∧  ( 𝑁  −  𝑀 )  ∈  ℕ )  →  ( FermatNo ‘ 𝑀 )  ∥  ( ( FermatNo ‘ ( 𝑀  +  ( 𝑁  −  𝑀 ) ) )  −  2 ) ) | 
						
							| 8 | 1 6 7 | syl2anc | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝑀  ∈  ℕ0  ∧  𝑀  <  𝑁 )  →  ( FermatNo ‘ 𝑀 )  ∥  ( ( FermatNo ‘ ( 𝑀  +  ( 𝑁  −  𝑀 ) ) )  −  2 ) ) | 
						
							| 9 |  | nn0cn | ⊢ ( 𝑁  ∈  ℕ0  →  𝑁  ∈  ℂ ) | 
						
							| 10 |  | nn0cn | ⊢ ( 𝑀  ∈  ℕ0  →  𝑀  ∈  ℂ ) | 
						
							| 11 | 9 10 | anim12ci | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝑀  ∈  ℕ0 )  →  ( 𝑀  ∈  ℂ  ∧  𝑁  ∈  ℂ ) ) | 
						
							| 12 | 11 | 3adant3 | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝑀  ∈  ℕ0  ∧  𝑀  <  𝑁 )  →  ( 𝑀  ∈  ℂ  ∧  𝑁  ∈  ℂ ) ) | 
						
							| 13 |  | pncan3 | ⊢ ( ( 𝑀  ∈  ℂ  ∧  𝑁  ∈  ℂ )  →  ( 𝑀  +  ( 𝑁  −  𝑀 ) )  =  𝑁 ) | 
						
							| 14 | 12 13 | syl | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝑀  ∈  ℕ0  ∧  𝑀  <  𝑁 )  →  ( 𝑀  +  ( 𝑁  −  𝑀 ) )  =  𝑁 ) | 
						
							| 15 | 14 | eqcomd | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝑀  ∈  ℕ0  ∧  𝑀  <  𝑁 )  →  𝑁  =  ( 𝑀  +  ( 𝑁  −  𝑀 ) ) ) | 
						
							| 16 | 15 | fveq2d | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝑀  ∈  ℕ0  ∧  𝑀  <  𝑁 )  →  ( FermatNo ‘ 𝑁 )  =  ( FermatNo ‘ ( 𝑀  +  ( 𝑁  −  𝑀 ) ) ) ) | 
						
							| 17 | 16 | oveq1d | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝑀  ∈  ℕ0  ∧  𝑀  <  𝑁 )  →  ( ( FermatNo ‘ 𝑁 )  −  2 )  =  ( ( FermatNo ‘ ( 𝑀  +  ( 𝑁  −  𝑀 ) ) )  −  2 ) ) | 
						
							| 18 | 8 17 | breqtrrd | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝑀  ∈  ℕ0  ∧  𝑀  <  𝑁 )  →  ( FermatNo ‘ 𝑀 )  ∥  ( ( FermatNo ‘ 𝑁 )  −  2 ) ) |