Without using log
IntuitionApproachComplexity
Time complexity:

Space complexity:
Code
# Intuition
<!-- Describe your first thoughts on how to solve this problem. -->

# Approach
<!-- Describe your approach to solving the problem. -->

# Complexity
- Time complexity:
<!-- Add your time complexity here, e.g. $$O(n)$$ -->

- Space complexity:
<!-- Add your space complexity here, e.g. $$O(n)$$ -->

# Code
```csharp []
public class Solution {
    public int SmallestNumber(int n)
    {
        int res = 0;
        int j = 0;
        for (int i = 1; i <= n; i = i * 2)
        {
            res += (int)Math.Pow(2, j++);
        }

        return res;
    }
}
```
['C#']