Attempt:
- If the Ns appear next to each other
I treat as if there is 1 B, 3 As, 1 N which leads to $\frac{5!}{1!3!1!}$
- Every N is followed by an A
I count the possible "unique characters" as NA-2, A-1, B-1 so I end up with $\frac{4!}{2!}$
- the two Ns must be separated
No matter how much I think about it, I'm not sure I can get an answer that doesn't lead me with a headache.