| Step | Hyp | Ref | Expression | 
						
							| 1 |  | aaliou3lem.c | ⊢ 𝐹  =  ( 𝑎  ∈  ℕ  ↦  ( 2 ↑ - ( ! ‘ 𝑎 ) ) ) | 
						
							| 2 |  | aaliou3lem.d | ⊢ 𝐿  =  Σ 𝑏  ∈  ℕ ( 𝐹 ‘ 𝑏 ) | 
						
							| 3 |  | aaliou3lem.e | ⊢ 𝐻  =  ( 𝑐  ∈  ℕ  ↦  Σ 𝑏  ∈  ( 1 ... 𝑐 ) ( 𝐹 ‘ 𝑏 ) ) | 
						
							| 4 |  | oveq2 | ⊢ ( 𝑐  =  𝐴  →  ( 1 ... 𝑐 )  =  ( 1 ... 𝐴 ) ) | 
						
							| 5 | 4 | sumeq1d | ⊢ ( 𝑐  =  𝐴  →  Σ 𝑏  ∈  ( 1 ... 𝑐 ) ( 𝐹 ‘ 𝑏 )  =  Σ 𝑏  ∈  ( 1 ... 𝐴 ) ( 𝐹 ‘ 𝑏 ) ) | 
						
							| 6 |  | sumex | ⊢ Σ 𝑏  ∈  ( 1 ... 𝐴 ) ( 𝐹 ‘ 𝑏 )  ∈  V | 
						
							| 7 | 5 3 6 | fvmpt | ⊢ ( 𝐴  ∈  ℕ  →  ( 𝐻 ‘ 𝐴 )  =  Σ 𝑏  ∈  ( 1 ... 𝐴 ) ( 𝐹 ‘ 𝑏 ) ) | 
						
							| 8 |  | fzfid | ⊢ ( 𝐴  ∈  ℕ  →  ( 1 ... 𝐴 )  ∈  Fin ) | 
						
							| 9 |  | elfznn | ⊢ ( 𝑏  ∈  ( 1 ... 𝐴 )  →  𝑏  ∈  ℕ ) | 
						
							| 10 | 9 | adantl | ⊢ ( ( 𝐴  ∈  ℕ  ∧  𝑏  ∈  ( 1 ... 𝐴 ) )  →  𝑏  ∈  ℕ ) | 
						
							| 11 |  | fveq2 | ⊢ ( 𝑎  =  𝑏  →  ( ! ‘ 𝑎 )  =  ( ! ‘ 𝑏 ) ) | 
						
							| 12 | 11 | negeqd | ⊢ ( 𝑎  =  𝑏  →  - ( ! ‘ 𝑎 )  =  - ( ! ‘ 𝑏 ) ) | 
						
							| 13 | 12 | oveq2d | ⊢ ( 𝑎  =  𝑏  →  ( 2 ↑ - ( ! ‘ 𝑎 ) )  =  ( 2 ↑ - ( ! ‘ 𝑏 ) ) ) | 
						
							| 14 |  | ovex | ⊢ ( 2 ↑ - ( ! ‘ 𝑏 ) )  ∈  V | 
						
							| 15 | 13 1 14 | fvmpt | ⊢ ( 𝑏  ∈  ℕ  →  ( 𝐹 ‘ 𝑏 )  =  ( 2 ↑ - ( ! ‘ 𝑏 ) ) ) | 
						
							| 16 |  | 2rp | ⊢ 2  ∈  ℝ+ | 
						
							| 17 |  | nnnn0 | ⊢ ( 𝑏  ∈  ℕ  →  𝑏  ∈  ℕ0 ) | 
						
							| 18 | 17 | faccld | ⊢ ( 𝑏  ∈  ℕ  →  ( ! ‘ 𝑏 )  ∈  ℕ ) | 
						
							| 19 | 18 | nnzd | ⊢ ( 𝑏  ∈  ℕ  →  ( ! ‘ 𝑏 )  ∈  ℤ ) | 
						
							| 20 | 19 | znegcld | ⊢ ( 𝑏  ∈  ℕ  →  - ( ! ‘ 𝑏 )  ∈  ℤ ) | 
						
							| 21 |  | rpexpcl | ⊢ ( ( 2  ∈  ℝ+  ∧  - ( ! ‘ 𝑏 )  ∈  ℤ )  →  ( 2 ↑ - ( ! ‘ 𝑏 ) )  ∈  ℝ+ ) | 
						
							| 22 | 16 20 21 | sylancr | ⊢ ( 𝑏  ∈  ℕ  →  ( 2 ↑ - ( ! ‘ 𝑏 ) )  ∈  ℝ+ ) | 
						
							| 23 | 22 | rpred | ⊢ ( 𝑏  ∈  ℕ  →  ( 2 ↑ - ( ! ‘ 𝑏 ) )  ∈  ℝ ) | 
						
							| 24 | 15 23 | eqeltrd | ⊢ ( 𝑏  ∈  ℕ  →  ( 𝐹 ‘ 𝑏 )  ∈  ℝ ) | 
						
							| 25 | 10 24 | syl | ⊢ ( ( 𝐴  ∈  ℕ  ∧  𝑏  ∈  ( 1 ... 𝐴 ) )  →  ( 𝐹 ‘ 𝑏 )  ∈  ℝ ) | 
						
							| 26 | 8 25 | fsumrecl | ⊢ ( 𝐴  ∈  ℕ  →  Σ 𝑏  ∈  ( 1 ... 𝐴 ) ( 𝐹 ‘ 𝑏 )  ∈  ℝ ) | 
						
							| 27 | 7 26 | eqeltrd | ⊢ ( 𝐴  ∈  ℕ  →  ( 𝐻 ‘ 𝐴 )  ∈  ℝ ) |