Functional way to check if array of numbers is sequential

Question

Let\'s say that an array is sequential when each successful element has the value of previous element + 1. Suppose I have an array of numbers like {5,6,7,

Answer 1

Using Linq:

    public static bool IsSequential(int[] a)
    {
        return Enumerable.Range(1, a.Length - 1).All(i => a[i] - 1 == a[i - 1]);
    }