| Step | Hyp | Ref | Expression | 
						
							| 1 |  | eulerpart.p | ⊢ 𝑃  =  { 𝑓  ∈  ( ℕ0  ↑m  ℕ )  ∣  ( ( ◡ 𝑓  “  ℕ )  ∈  Fin  ∧  Σ 𝑘  ∈  ℕ ( ( 𝑓 ‘ 𝑘 )  ·  𝑘 )  =  𝑁 ) } | 
						
							| 2 |  | nn0ex | ⊢ ℕ0  ∈  V | 
						
							| 3 |  | nnex | ⊢ ℕ  ∈  V | 
						
							| 4 | 2 3 | elmap | ⊢ ( 𝐴  ∈  ( ℕ0  ↑m  ℕ )  ↔  𝐴 : ℕ ⟶ ℕ0 ) | 
						
							| 5 | 4 | anbi1i | ⊢ ( ( 𝐴  ∈  ( ℕ0  ↑m  ℕ )  ∧  ( ( ◡ 𝐴  “  ℕ )  ∈  Fin  ∧  Σ 𝑘  ∈  ℕ ( ( 𝐴 ‘ 𝑘 )  ·  𝑘 )  =  𝑁 ) )  ↔  ( 𝐴 : ℕ ⟶ ℕ0  ∧  ( ( ◡ 𝐴  “  ℕ )  ∈  Fin  ∧  Σ 𝑘  ∈  ℕ ( ( 𝐴 ‘ 𝑘 )  ·  𝑘 )  =  𝑁 ) ) ) | 
						
							| 6 |  | cnveq | ⊢ ( 𝑓  =  𝐴  →  ◡ 𝑓  =  ◡ 𝐴 ) | 
						
							| 7 | 6 | imaeq1d | ⊢ ( 𝑓  =  𝐴  →  ( ◡ 𝑓  “  ℕ )  =  ( ◡ 𝐴  “  ℕ ) ) | 
						
							| 8 | 7 | eleq1d | ⊢ ( 𝑓  =  𝐴  →  ( ( ◡ 𝑓  “  ℕ )  ∈  Fin  ↔  ( ◡ 𝐴  “  ℕ )  ∈  Fin ) ) | 
						
							| 9 |  | fveq1 | ⊢ ( 𝑓  =  𝐴  →  ( 𝑓 ‘ 𝑘 )  =  ( 𝐴 ‘ 𝑘 ) ) | 
						
							| 10 | 9 | oveq1d | ⊢ ( 𝑓  =  𝐴  →  ( ( 𝑓 ‘ 𝑘 )  ·  𝑘 )  =  ( ( 𝐴 ‘ 𝑘 )  ·  𝑘 ) ) | 
						
							| 11 | 10 | sumeq2sdv | ⊢ ( 𝑓  =  𝐴  →  Σ 𝑘  ∈  ℕ ( ( 𝑓 ‘ 𝑘 )  ·  𝑘 )  =  Σ 𝑘  ∈  ℕ ( ( 𝐴 ‘ 𝑘 )  ·  𝑘 ) ) | 
						
							| 12 | 11 | eqeq1d | ⊢ ( 𝑓  =  𝐴  →  ( Σ 𝑘  ∈  ℕ ( ( 𝑓 ‘ 𝑘 )  ·  𝑘 )  =  𝑁  ↔  Σ 𝑘  ∈  ℕ ( ( 𝐴 ‘ 𝑘 )  ·  𝑘 )  =  𝑁 ) ) | 
						
							| 13 | 8 12 | anbi12d | ⊢ ( 𝑓  =  𝐴  →  ( ( ( ◡ 𝑓  “  ℕ )  ∈  Fin  ∧  Σ 𝑘  ∈  ℕ ( ( 𝑓 ‘ 𝑘 )  ·  𝑘 )  =  𝑁 )  ↔  ( ( ◡ 𝐴  “  ℕ )  ∈  Fin  ∧  Σ 𝑘  ∈  ℕ ( ( 𝐴 ‘ 𝑘 )  ·  𝑘 )  =  𝑁 ) ) ) | 
						
							| 14 | 13 1 | elrab2 | ⊢ ( 𝐴  ∈  𝑃  ↔  ( 𝐴  ∈  ( ℕ0  ↑m  ℕ )  ∧  ( ( ◡ 𝐴  “  ℕ )  ∈  Fin  ∧  Σ 𝑘  ∈  ℕ ( ( 𝐴 ‘ 𝑘 )  ·  𝑘 )  =  𝑁 ) ) ) | 
						
							| 15 |  | 3anass | ⊢ ( ( 𝐴 : ℕ ⟶ ℕ0  ∧  ( ◡ 𝐴  “  ℕ )  ∈  Fin  ∧  Σ 𝑘  ∈  ℕ ( ( 𝐴 ‘ 𝑘 )  ·  𝑘 )  =  𝑁 )  ↔  ( 𝐴 : ℕ ⟶ ℕ0  ∧  ( ( ◡ 𝐴  “  ℕ )  ∈  Fin  ∧  Σ 𝑘  ∈  ℕ ( ( 𝐴 ‘ 𝑘 )  ·  𝑘 )  =  𝑁 ) ) ) | 
						
							| 16 | 5 14 15 | 3bitr4i | ⊢ ( 𝐴  ∈  𝑃  ↔  ( 𝐴 : ℕ ⟶ ℕ0  ∧  ( ◡ 𝐴  “  ℕ )  ∈  Fin  ∧  Σ 𝑘  ∈  ℕ ( ( 𝐴 ‘ 𝑘 )  ·  𝑘 )  =  𝑁 ) ) |