Tighter bounds in the prime number theorem

johndcook.comJohn2026年01月16日 15:50

The most elementary form of the prime number theorem says that π(x), the number of prime numbers less than x, is asymptotically equal to x / log(x). That’s true, but a more accurate result says π(x) is asymptotically equal to li(x) where

\text{li}(x) = \int_0^x \frac{dt}{\log t}

Five years ago I wrote about a result that was new at the time, giving a bound on |π(x) − li(x)| for x > exp(2000). This morning I saw a result in a blog post by Terence Tao that says

\left| \pi(x) - \text{li}(x) \right| \leq 9.2211\, x\sqrt{\log(x)} \exp\left( -0.8476 \sqrt{\log(x)} \right)

for all x ≥ 2. The result comes from this paper.

The new bound has the same form as the bound from five years ago but with smaller constants.

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