| Step | Hyp | Ref | Expression | 
						
							| 1 |  | evenz | ⊢ ( 𝑍  ∈   Even   →  𝑍  ∈  ℤ ) | 
						
							| 2 | 1 | peano2zd | ⊢ ( 𝑍  ∈   Even   →  ( 𝑍  +  1 )  ∈  ℤ ) | 
						
							| 3 |  | iseven | ⊢ ( 𝑍  ∈   Even   ↔  ( 𝑍  ∈  ℤ  ∧  ( 𝑍  /  2 )  ∈  ℤ ) ) | 
						
							| 4 |  | zcn | ⊢ ( 𝑍  ∈  ℤ  →  𝑍  ∈  ℂ ) | 
						
							| 5 |  | pncan1 | ⊢ ( 𝑍  ∈  ℂ  →  ( ( 𝑍  +  1 )  −  1 )  =  𝑍 ) | 
						
							| 6 | 4 5 | syl | ⊢ ( 𝑍  ∈  ℤ  →  ( ( 𝑍  +  1 )  −  1 )  =  𝑍 ) | 
						
							| 7 | 6 | eqcomd | ⊢ ( 𝑍  ∈  ℤ  →  𝑍  =  ( ( 𝑍  +  1 )  −  1 ) ) | 
						
							| 8 | 7 | oveq1d | ⊢ ( 𝑍  ∈  ℤ  →  ( 𝑍  /  2 )  =  ( ( ( 𝑍  +  1 )  −  1 )  /  2 ) ) | 
						
							| 9 | 8 | eleq1d | ⊢ ( 𝑍  ∈  ℤ  →  ( ( 𝑍  /  2 )  ∈  ℤ  ↔  ( ( ( 𝑍  +  1 )  −  1 )  /  2 )  ∈  ℤ ) ) | 
						
							| 10 | 9 | biimpa | ⊢ ( ( 𝑍  ∈  ℤ  ∧  ( 𝑍  /  2 )  ∈  ℤ )  →  ( ( ( 𝑍  +  1 )  −  1 )  /  2 )  ∈  ℤ ) | 
						
							| 11 | 3 10 | sylbi | ⊢ ( 𝑍  ∈   Even   →  ( ( ( 𝑍  +  1 )  −  1 )  /  2 )  ∈  ℤ ) | 
						
							| 12 |  | isodd2 | ⊢ ( ( 𝑍  +  1 )  ∈   Odd   ↔  ( ( 𝑍  +  1 )  ∈  ℤ  ∧  ( ( ( 𝑍  +  1 )  −  1 )  /  2 )  ∈  ℤ ) ) | 
						
							| 13 | 2 11 12 | sylanbrc | ⊢ ( 𝑍  ∈   Even   →  ( 𝑍  +  1 )  ∈   Odd  ) |