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Description: The second Chebyshev function at 1 . (Contributed by Mario Carneiro, 9-Apr-2016)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | chp1 | ⊢ ( ψ ‘ 1 ) = 0 |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | 1re | ⊢ 1 ∈ ℝ | |
| 2 | chpval | ⊢ ( 1 ∈ ℝ → ( ψ ‘ 1 ) = Σ 𝑥 ∈ ( 1 ... ( ⌊ ‘ 1 ) ) ( Λ ‘ 𝑥 ) ) | |
| 3 | 1 2 | ax-mp | ⊢ ( ψ ‘ 1 ) = Σ 𝑥 ∈ ( 1 ... ( ⌊ ‘ 1 ) ) ( Λ ‘ 𝑥 ) |
| 4 | elfz1eq | ⊢ ( 𝑥 ∈ ( 1 ... 1 ) → 𝑥 = 1 ) | |
| 5 | 4 | fveq2d | ⊢ ( 𝑥 ∈ ( 1 ... 1 ) → ( Λ ‘ 𝑥 ) = ( Λ ‘ 1 ) ) |
| 6 | vma1 | ⊢ ( Λ ‘ 1 ) = 0 | |
| 7 | 5 6 | eqtrdi | ⊢ ( 𝑥 ∈ ( 1 ... 1 ) → ( Λ ‘ 𝑥 ) = 0 ) |
| 8 | 1z | ⊢ 1 ∈ ℤ | |
| 9 | flid | ⊢ ( 1 ∈ ℤ → ( ⌊ ‘ 1 ) = 1 ) | |
| 10 | 8 9 | ax-mp | ⊢ ( ⌊ ‘ 1 ) = 1 |
| 11 | 10 | oveq2i | ⊢ ( 1 ... ( ⌊ ‘ 1 ) ) = ( 1 ... 1 ) |
| 12 | 7 11 | eleq2s | ⊢ ( 𝑥 ∈ ( 1 ... ( ⌊ ‘ 1 ) ) → ( Λ ‘ 𝑥 ) = 0 ) |
| 13 | 12 | sumeq2i | ⊢ Σ 𝑥 ∈ ( 1 ... ( ⌊ ‘ 1 ) ) ( Λ ‘ 𝑥 ) = Σ 𝑥 ∈ ( 1 ... ( ⌊ ‘ 1 ) ) 0 |
| 14 | fzfi | ⊢ ( 1 ... ( ⌊ ‘ 1 ) ) ∈ Fin | |
| 15 | 14 | olci | ⊢ ( ( 1 ... ( ⌊ ‘ 1 ) ) ⊆ ( ℤ≥ ‘ 1 ) ∨ ( 1 ... ( ⌊ ‘ 1 ) ) ∈ Fin ) |
| 16 | sumz | ⊢ ( ( ( 1 ... ( ⌊ ‘ 1 ) ) ⊆ ( ℤ≥ ‘ 1 ) ∨ ( 1 ... ( ⌊ ‘ 1 ) ) ∈ Fin ) → Σ 𝑥 ∈ ( 1 ... ( ⌊ ‘ 1 ) ) 0 = 0 ) | |
| 17 | 15 16 | ax-mp | ⊢ Σ 𝑥 ∈ ( 1 ... ( ⌊ ‘ 1 ) ) 0 = 0 |
| 18 | 3 13 17 | 3eqtri | ⊢ ( ψ ‘ 1 ) = 0 |