The
offset logarithmic integral is a
non-elementary function Li(
x) very similar to the
logarithmic integral function li(
x), defined such that:
- Li(x) = li(x) - li(2).
Explicitly, this means
- <math> {\rm Li} (x) = \int_{2}^{x} \frac{dt}{\ln (t)} \; . </math>
It is often used in formulations of the prime number theorem.