| Step | Hyp | Ref | Expression | 
						
							| 1 |  | fveq2 | ⊢ ( 𝑥  =  0  →  ( ! ‘ 𝑥 )  =  ( ! ‘ 0 ) ) | 
						
							| 2 | 1 | breq2d | ⊢ ( 𝑥  =  0  →  ( 𝑃  ∥  ( ! ‘ 𝑥 )  ↔  𝑃  ∥  ( ! ‘ 0 ) ) ) | 
						
							| 3 |  | breq2 | ⊢ ( 𝑥  =  0  →  ( 𝑃  ≤  𝑥  ↔  𝑃  ≤  0 ) ) | 
						
							| 4 | 2 3 | imbi12d | ⊢ ( 𝑥  =  0  →  ( ( 𝑃  ∥  ( ! ‘ 𝑥 )  →  𝑃  ≤  𝑥 )  ↔  ( 𝑃  ∥  ( ! ‘ 0 )  →  𝑃  ≤  0 ) ) ) | 
						
							| 5 | 4 | imbi2d | ⊢ ( 𝑥  =  0  →  ( ( 𝑃  ∈  ℙ  →  ( 𝑃  ∥  ( ! ‘ 𝑥 )  →  𝑃  ≤  𝑥 ) )  ↔  ( 𝑃  ∈  ℙ  →  ( 𝑃  ∥  ( ! ‘ 0 )  →  𝑃  ≤  0 ) ) ) ) | 
						
							| 6 |  | fveq2 | ⊢ ( 𝑥  =  𝑘  →  ( ! ‘ 𝑥 )  =  ( ! ‘ 𝑘 ) ) | 
						
							| 7 | 6 | breq2d | ⊢ ( 𝑥  =  𝑘  →  ( 𝑃  ∥  ( ! ‘ 𝑥 )  ↔  𝑃  ∥  ( ! ‘ 𝑘 ) ) ) | 
						
							| 8 |  | breq2 | ⊢ ( 𝑥  =  𝑘  →  ( 𝑃  ≤  𝑥  ↔  𝑃  ≤  𝑘 ) ) | 
						
							| 9 | 7 8 | imbi12d | ⊢ ( 𝑥  =  𝑘  →  ( ( 𝑃  ∥  ( ! ‘ 𝑥 )  →  𝑃  ≤  𝑥 )  ↔  ( 𝑃  ∥  ( ! ‘ 𝑘 )  →  𝑃  ≤  𝑘 ) ) ) | 
						
							| 10 | 9 | imbi2d | ⊢ ( 𝑥  =  𝑘  →  ( ( 𝑃  ∈  ℙ  →  ( 𝑃  ∥  ( ! ‘ 𝑥 )  →  𝑃  ≤  𝑥 ) )  ↔  ( 𝑃  ∈  ℙ  →  ( 𝑃  ∥  ( ! ‘ 𝑘 )  →  𝑃  ≤  𝑘 ) ) ) ) | 
						
							| 11 |  | fveq2 | ⊢ ( 𝑥  =  ( 𝑘  +  1 )  →  ( ! ‘ 𝑥 )  =  ( ! ‘ ( 𝑘  +  1 ) ) ) | 
						
							| 12 | 11 | breq2d | ⊢ ( 𝑥  =  ( 𝑘  +  1 )  →  ( 𝑃  ∥  ( ! ‘ 𝑥 )  ↔  𝑃  ∥  ( ! ‘ ( 𝑘  +  1 ) ) ) ) | 
						
							| 13 |  | breq2 | ⊢ ( 𝑥  =  ( 𝑘  +  1 )  →  ( 𝑃  ≤  𝑥  ↔  𝑃  ≤  ( 𝑘  +  1 ) ) ) | 
						
							| 14 | 12 13 | imbi12d | ⊢ ( 𝑥  =  ( 𝑘  +  1 )  →  ( ( 𝑃  ∥  ( ! ‘ 𝑥 )  →  𝑃  ≤  𝑥 )  ↔  ( 𝑃  ∥  ( ! ‘ ( 𝑘  +  1 ) )  →  𝑃  ≤  ( 𝑘  +  1 ) ) ) ) | 
						
							| 15 | 14 | imbi2d | ⊢ ( 𝑥  =  ( 𝑘  +  1 )  →  ( ( 𝑃  ∈  ℙ  →  ( 𝑃  ∥  ( ! ‘ 𝑥 )  →  𝑃  ≤  𝑥 ) )  ↔  ( 𝑃  ∈  ℙ  →  ( 𝑃  ∥  ( ! ‘ ( 𝑘  +  1 ) )  →  𝑃  ≤  ( 𝑘  +  1 ) ) ) ) ) | 
						
							| 16 |  | fveq2 | ⊢ ( 𝑥  =  𝑁  →  ( ! ‘ 𝑥 )  =  ( ! ‘ 𝑁 ) ) | 
						
							| 17 | 16 | breq2d | ⊢ ( 𝑥  =  𝑁  →  ( 𝑃  ∥  ( ! ‘ 𝑥 )  ↔  𝑃  ∥  ( ! ‘ 𝑁 ) ) ) | 
						
							| 18 |  | breq2 | ⊢ ( 𝑥  =  𝑁  →  ( 𝑃  ≤  𝑥  ↔  𝑃  ≤  𝑁 ) ) | 
						
							| 19 | 17 18 | imbi12d | ⊢ ( 𝑥  =  𝑁  →  ( ( 𝑃  ∥  ( ! ‘ 𝑥 )  →  𝑃  ≤  𝑥 )  ↔  ( 𝑃  ∥  ( ! ‘ 𝑁 )  →  𝑃  ≤  𝑁 ) ) ) | 
						
							| 20 | 19 | imbi2d | ⊢ ( 𝑥  =  𝑁  →  ( ( 𝑃  ∈  ℙ  →  ( 𝑃  ∥  ( ! ‘ 𝑥 )  →  𝑃  ≤  𝑥 ) )  ↔  ( 𝑃  ∈  ℙ  →  ( 𝑃  ∥  ( ! ‘ 𝑁 )  →  𝑃  ≤  𝑁 ) ) ) ) | 
						
							| 21 |  | fac0 | ⊢ ( ! ‘ 0 )  =  1 | 
						
							| 22 | 21 | breq2i | ⊢ ( 𝑃  ∥  ( ! ‘ 0 )  ↔  𝑃  ∥  1 ) | 
						
							| 23 |  | nprmdvds1 | ⊢ ( 𝑃  ∈  ℙ  →  ¬  𝑃  ∥  1 ) | 
						
							| 24 | 23 | pm2.21d | ⊢ ( 𝑃  ∈  ℙ  →  ( 𝑃  ∥  1  →  𝑃  ≤  0 ) ) | 
						
							| 25 | 22 24 | biimtrid | ⊢ ( 𝑃  ∈  ℙ  →  ( 𝑃  ∥  ( ! ‘ 0 )  →  𝑃  ≤  0 ) ) | 
						
							| 26 |  | facp1 | ⊢ ( 𝑘  ∈  ℕ0  →  ( ! ‘ ( 𝑘  +  1 ) )  =  ( ( ! ‘ 𝑘 )  ·  ( 𝑘  +  1 ) ) ) | 
						
							| 27 | 26 | adantr | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  ( ! ‘ ( 𝑘  +  1 ) )  =  ( ( ! ‘ 𝑘 )  ·  ( 𝑘  +  1 ) ) ) | 
						
							| 28 | 27 | breq2d | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  ( 𝑃  ∥  ( ! ‘ ( 𝑘  +  1 ) )  ↔  𝑃  ∥  ( ( ! ‘ 𝑘 )  ·  ( 𝑘  +  1 ) ) ) ) | 
						
							| 29 |  | simpr | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  𝑃  ∈  ℙ ) | 
						
							| 30 |  | faccl | ⊢ ( 𝑘  ∈  ℕ0  →  ( ! ‘ 𝑘 )  ∈  ℕ ) | 
						
							| 31 | 30 | adantr | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  ( ! ‘ 𝑘 )  ∈  ℕ ) | 
						
							| 32 | 31 | nnzd | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  ( ! ‘ 𝑘 )  ∈  ℤ ) | 
						
							| 33 |  | nn0p1nn | ⊢ ( 𝑘  ∈  ℕ0  →  ( 𝑘  +  1 )  ∈  ℕ ) | 
						
							| 34 | 33 | adantr | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  ( 𝑘  +  1 )  ∈  ℕ ) | 
						
							| 35 | 34 | nnzd | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  ( 𝑘  +  1 )  ∈  ℤ ) | 
						
							| 36 |  | euclemma | ⊢ ( ( 𝑃  ∈  ℙ  ∧  ( ! ‘ 𝑘 )  ∈  ℤ  ∧  ( 𝑘  +  1 )  ∈  ℤ )  →  ( 𝑃  ∥  ( ( ! ‘ 𝑘 )  ·  ( 𝑘  +  1 ) )  ↔  ( 𝑃  ∥  ( ! ‘ 𝑘 )  ∨  𝑃  ∥  ( 𝑘  +  1 ) ) ) ) | 
						
							| 37 | 29 32 35 36 | syl3anc | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  ( 𝑃  ∥  ( ( ! ‘ 𝑘 )  ·  ( 𝑘  +  1 ) )  ↔  ( 𝑃  ∥  ( ! ‘ 𝑘 )  ∨  𝑃  ∥  ( 𝑘  +  1 ) ) ) ) | 
						
							| 38 | 28 37 | bitrd | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  ( 𝑃  ∥  ( ! ‘ ( 𝑘  +  1 ) )  ↔  ( 𝑃  ∥  ( ! ‘ 𝑘 )  ∨  𝑃  ∥  ( 𝑘  +  1 ) ) ) ) | 
						
							| 39 |  | nn0re | ⊢ ( 𝑘  ∈  ℕ0  →  𝑘  ∈  ℝ ) | 
						
							| 40 | 39 | adantr | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  𝑘  ∈  ℝ ) | 
						
							| 41 | 40 | lep1d | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  𝑘  ≤  ( 𝑘  +  1 ) ) | 
						
							| 42 |  | prmz | ⊢ ( 𝑃  ∈  ℙ  →  𝑃  ∈  ℤ ) | 
						
							| 43 | 42 | adantl | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  𝑃  ∈  ℤ ) | 
						
							| 44 | 43 | zred | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  𝑃  ∈  ℝ ) | 
						
							| 45 | 34 | nnred | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  ( 𝑘  +  1 )  ∈  ℝ ) | 
						
							| 46 |  | letr | ⊢ ( ( 𝑃  ∈  ℝ  ∧  𝑘  ∈  ℝ  ∧  ( 𝑘  +  1 )  ∈  ℝ )  →  ( ( 𝑃  ≤  𝑘  ∧  𝑘  ≤  ( 𝑘  +  1 ) )  →  𝑃  ≤  ( 𝑘  +  1 ) ) ) | 
						
							| 47 | 44 40 45 46 | syl3anc | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  ( ( 𝑃  ≤  𝑘  ∧  𝑘  ≤  ( 𝑘  +  1 ) )  →  𝑃  ≤  ( 𝑘  +  1 ) ) ) | 
						
							| 48 | 41 47 | mpan2d | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  ( 𝑃  ≤  𝑘  →  𝑃  ≤  ( 𝑘  +  1 ) ) ) | 
						
							| 49 | 48 | imim2d | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  ( ( 𝑃  ∥  ( ! ‘ 𝑘 )  →  𝑃  ≤  𝑘 )  →  ( 𝑃  ∥  ( ! ‘ 𝑘 )  →  𝑃  ≤  ( 𝑘  +  1 ) ) ) ) | 
						
							| 50 | 49 | com23 | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  ( 𝑃  ∥  ( ! ‘ 𝑘 )  →  ( ( 𝑃  ∥  ( ! ‘ 𝑘 )  →  𝑃  ≤  𝑘 )  →  𝑃  ≤  ( 𝑘  +  1 ) ) ) ) | 
						
							| 51 |  | dvdsle | ⊢ ( ( 𝑃  ∈  ℤ  ∧  ( 𝑘  +  1 )  ∈  ℕ )  →  ( 𝑃  ∥  ( 𝑘  +  1 )  →  𝑃  ≤  ( 𝑘  +  1 ) ) ) | 
						
							| 52 | 43 34 51 | syl2anc | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  ( 𝑃  ∥  ( 𝑘  +  1 )  →  𝑃  ≤  ( 𝑘  +  1 ) ) ) | 
						
							| 53 | 52 | a1dd | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  ( 𝑃  ∥  ( 𝑘  +  1 )  →  ( ( 𝑃  ∥  ( ! ‘ 𝑘 )  →  𝑃  ≤  𝑘 )  →  𝑃  ≤  ( 𝑘  +  1 ) ) ) ) | 
						
							| 54 | 50 53 | jaod | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  ( ( 𝑃  ∥  ( ! ‘ 𝑘 )  ∨  𝑃  ∥  ( 𝑘  +  1 ) )  →  ( ( 𝑃  ∥  ( ! ‘ 𝑘 )  →  𝑃  ≤  𝑘 )  →  𝑃  ≤  ( 𝑘  +  1 ) ) ) ) | 
						
							| 55 | 38 54 | sylbid | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  ( 𝑃  ∥  ( ! ‘ ( 𝑘  +  1 ) )  →  ( ( 𝑃  ∥  ( ! ‘ 𝑘 )  →  𝑃  ≤  𝑘 )  →  𝑃  ≤  ( 𝑘  +  1 ) ) ) ) | 
						
							| 56 | 55 | com23 | ⊢ ( ( 𝑘  ∈  ℕ0  ∧  𝑃  ∈  ℙ )  →  ( ( 𝑃  ∥  ( ! ‘ 𝑘 )  →  𝑃  ≤  𝑘 )  →  ( 𝑃  ∥  ( ! ‘ ( 𝑘  +  1 ) )  →  𝑃  ≤  ( 𝑘  +  1 ) ) ) ) | 
						
							| 57 | 56 | ex | ⊢ ( 𝑘  ∈  ℕ0  →  ( 𝑃  ∈  ℙ  →  ( ( 𝑃  ∥  ( ! ‘ 𝑘 )  →  𝑃  ≤  𝑘 )  →  ( 𝑃  ∥  ( ! ‘ ( 𝑘  +  1 ) )  →  𝑃  ≤  ( 𝑘  +  1 ) ) ) ) ) | 
						
							| 58 | 57 | a2d | ⊢ ( 𝑘  ∈  ℕ0  →  ( ( 𝑃  ∈  ℙ  →  ( 𝑃  ∥  ( ! ‘ 𝑘 )  →  𝑃  ≤  𝑘 ) )  →  ( 𝑃  ∈  ℙ  →  ( 𝑃  ∥  ( ! ‘ ( 𝑘  +  1 ) )  →  𝑃  ≤  ( 𝑘  +  1 ) ) ) ) ) | 
						
							| 59 | 5 10 15 20 25 58 | nn0ind | ⊢ ( 𝑁  ∈  ℕ0  →  ( 𝑃  ∈  ℙ  →  ( 𝑃  ∥  ( ! ‘ 𝑁 )  →  𝑃  ≤  𝑁 ) ) ) | 
						
							| 60 | 59 | 3imp | ⊢ ( ( 𝑁  ∈  ℕ0  ∧  𝑃  ∈  ℙ  ∧  𝑃  ∥  ( ! ‘ 𝑁 ) )  →  𝑃  ≤  𝑁 ) |