Generate N random and unique numbers within a range

Question

What is an efficient way of generating N unique numbers within a given range using C#? For example, generate 6 unique numbers between 1 and 50. A lazy way would be to simply

Answer 1

var random = new Random();
var intArray = Enumerable.Range(0, 4).OrderBy(t => random.Next()).ToArray();

This array will contain 5 random numbers from 0 to 4.

or

  var intArray = Enumerable.Range(0, 10).OrderBy(t => random.Next()).Take(5).ToArray();

This array will contain 5 random numbers between 0 to 10.

int firstNumber = intArray[0];
int secondNumber = intArray[1];
int thirdNumber = intArray[2];
int fourthNumber = intArray[3];
int fifthNumber = intArray[4];