Rosser's theorem

In number theory, Rosser's theorem states that the ${\displaystyle n}$th prime number is greater than ${\displaystyle n\log n}$, where ${\displaystyle \log }$is the natural logarithm function. It was published by J. Barkley Rosser in 1939.

Its full statement is:

Let ${\displaystyle p_{n}}$be the ${\displaystyle n}$th prime number. Then for ${\displaystyle n\geq 1}$

${\displaystyle p_{n}>n\log n.}$

In 1999, Pierre Dusart proved a tighter lower bound:

${\displaystyle p_{n}>n(\log n+\log \log n-1).}$

• Prime number theorem

• Rosser's theorem article on Wolfram Mathworld.