How about simplifying?:
public class LetterData
{
public DirectionsType[] Directions;
public RotationsType[] Rotations;
}
LetterData[] myVar = new LetterData[25];
...
myVar[i].Directions = new DirectionsType[n];
...
myVar[i].Directions[k] = value;
Answer for EDIT:
public class LetterData
{
public int[] distance;
public int[] rotation;
}
public class MyClass
{
public LetterData[] sequence = new LetterData[25];
void Start ()
{
for (int i = 0; i < 25; i++)
{
sequence[i] = new LetterData();
sequence[i].distance = new int[2];
sequence[i].rotation = new int[2];
}
}
}
...
MyClass m = new MyClass();
m.Start();