I am interested in the number of components (denoted by $N$) of the Pretzel Link $(p_1,\ldots,p_n)$. I understand the following facts about this:
- Each $p_i$ can be considered as $0$ or $1$, depends on the parity of $p_i$;
- When $n$ and $p_i$'s are all odd, or when exactly one $p_i$ is even, $N=1$;
- When $n$ is even and $p_i$'s are all odd, $N=2$.
Question: Is there a general formula for computing $N$ as a function of $p_1,\ldots,p_n$ and $n$?
By the way, though this question is from topology, I feel it more like a combinatoric question and thus have tagged it accordingly.
Answer: When all $p_i$'s are odd, $N=\dfrac{3-(-1)^n}{2}$; when at least two $p_i$'s are even, $N$ equals to the number of even $p_i$'s.
This generalises the condition from Wikipedia about when a Pretzel link is a knot.