Random number from a specific group of numbers? (not Range)

Taken from the Scripting Overview:

// Loads a random level from the level list

Application.LoadLevel(Random.Range(0, Application.levelCount));

If I had for example 10 levels, how would I load a random level between levels 2,3,6 and 9?

Put the specific group of numbers you want to choose randomly from in an ordered list, choose a random item from that ordered list, load the level.

int[] randomLevels = new int[] {2, 3, 6, 9};
Application.LoadLevel(randomLevels[Random.Range(0, randomLevels.Length)]);

Try :

int[]  MyLevelsToLoad = new int[] { 2, 3, 6, 9 };
int RandomLevelIndex = (int) Math.Min( MyLevelsToLoad.Length-1, Random.Range( 0, MyLevelsToLoad.Length ) );
Application.LoadLevel( RandomLevelIndex );