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A Greek pi of a number, counting primes rather than measuring circles.
Also known as: Prime counting function, Pi of x, Prime pi
π(x) counts the primes up to x, and its notation is an outright collision with the circle constant — the same letter, in the same italic, meaning something unrelated. The prime number theorem says it grows like x over the natural logarithm of x.
Denotes the number of primes not exceeding a given value.
Contexts: Mathematics
Collides with the circle constant π: the two are distinguished only by whether an argument follows, which is a real hazard in mixed text.
Contexts: Mathematics
Is asymptotic to x divided by the natural logarithm of x, which is the prime number theorem.
Contexts: Mathematics
A Greek lowercase pi — two descending strokes under a horizontal bar — followed by a bracketed variable.