Metamath Proof Explorer


Theorem ppi1sum

Description: Value of the prime-counting function pi for 1, according to Ján Mináč. (Contributed by AV, 4-Apr-2026)

Ref Expression
Assertion ppi1sum ( π ‘ 1 ) = Σ 𝑘 ∈ ∅ ( ⌊ ‘ ( ( ( ( ! ‘ ( 𝑘 − 1 ) ) + 1 ) / 𝑘 ) − ( ⌊ ‘ ( ( ! ‘ ( 𝑘 − 1 ) ) / 𝑘 ) ) ) )

Proof

Step Hyp Ref Expression
1 ppi1 ( π ‘ 1 ) = 0
2 sum0 Σ 𝑘 ∈ ∅ ( ⌊ ‘ ( ( ( ( ! ‘ ( 𝑘 − 1 ) ) + 1 ) / 𝑘 ) − ( ⌊ ‘ ( ( ! ‘ ( 𝑘 − 1 ) ) / 𝑘 ) ) ) ) = 0
3 1 2 eqtr4i ( π ‘ 1 ) = Σ 𝑘 ∈ ∅ ( ⌊ ‘ ( ( ( ( ! ‘ ( 𝑘 − 1 ) ) + 1 ) / 𝑘 ) − ( ⌊ ‘ ( ( ! ‘ ( 𝑘 − 1 ) ) / 𝑘 ) ) ) )