Bertrand-Chebyshev theorem

== English == === Etymology === From the surname of Joseph Louis François Bertrand, who conjectured the theorem, and the surname of Pafnuty Chebyshev who proved it. === Proper noun === Bertrand-Chebyshev theorem (mathematics) the theorem that there is at least one prime number between n and 2n for every n>1, i.e.: ∀ n ∈ N : n > 1 ⇒ ∃ p ∈ P : n < p < 2 n {\displaystyle \forall n\in \mathbb {N} :n>1\Rightarrow \exists p\in \mathbb {P} :n<p<2n}