For problems involving either the product of the first n primes or the product of all primes up to and including n.
The former definition uses the notation $p_n\#$, while the latter is denoted $n\#$. We also define $p_0\#=1$.
In the first notation we have $$\lim_{n\to\infty}p_n \#^{\frac{1}{p_n}}=e,$$
while in the second, the natural logarithm of the primorials defines the first Chebyshev function.
Every highly composite number (A002182) is a product of primorials.
