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Smallest $m > 0$ such that there are no primes between $nm$ and $n(m+1)$ inclusive.

Sierpinski's conjecture (1958) is precisely that a(n) >= n for all n.

References:

namespace OeisA110835open Nat Set

The primary defining sequence a. $a(n)$ is the smallest $m > 0$ such that there are no primes between $n \cdot m$ and $n \cdot (m+1)$ inclusive.

noncomputable def a (n : ) : := let IsPrimeFreeInterval (m : ) : Prop := p : , p.Prime ¬ (n * m p p n * (m + 1)) let s : Set := {m : | m > 0 IsPrimeFreeInterval m} sInf s

Term theorems verifying the first few values of the sequence against the official OEIS b-file

hleast:IsLeast {m | m > 0 (p : ), Nat.Prime p ¬(1 * m p p 1 * (m + 1))} 8sInf {m | m > 0 (p : ), Nat.Prime p ¬(1 * m p p 1 * (m + 1))} = 8 All goals completed! 🐙hleast:IsLeast {m | m > 0 (p : ), Nat.Prime p ¬(2 * m p p 2 * (m + 1))} 4sInf {m | m > 0 (p : ), Nat.Prime p ¬(2 * m p p 2 * (m + 1))} = 4 All goals completed! 🐙hleast:IsLeast {m | m > 0 (p : ), Nat.Prime p ¬(3 * m p p 3 * (m + 1))} 8sInf {m | m > 0 (p : ), Nat.Prime p ¬(3 * m p p 3 * (m + 1))} = 8 All goals completed! 🐙

Sierpinski's conjecture (1958) is precisely that $a(n) >= n$ for all $n$.

@[category research open, AMS 11] theorem conjecture : n > 0, a n n := n > 0, OeisA110835.a n n All goals completed! 🐙end OeisA110835