A **Woodall number** is a number of the form \( n \cdot 2^n - 1 \), where \( n \) is a positive integer. For example, the first few Woodall numbers are 1, 7, 23, 63, etc.
Write a function `is_woodall(n)` that checks if a given number `n` is a Woodall number. The function should return `True` if the number is a Woodall number, and `False` otherwise.
#### Example Usage
```python [main.nopy]
print(is_woodall(7)) # True, because 7 = 1 * 2^3 - 1
print(is_woodall(23)) # True, because 23 = 3 * 2^3 - 1
print(is_woodall(10)) # False, because 10 is not a Woodall number
```
#### Constraints
- The input `n` will be a positive integer.
- The function should handle numbers up to 10^6 efficiently.