Compute the variance of a random variable in a coin experiment; see https://math.stackexchange.com/questions/2257188.

Question2257188.java

public class Question2257188 {
    final static int n = 4;
    
    public static void main(String [] args) {
        double s = 0;
        double s2 = 0;
        int [] [] permutations = Permutations.getPermutations(n);
        for (int [] p : permutations) {
            int sum = p [0] + 1;
            for (int i = 1;i < p.length;i++)
                sum += Math.abs(p [i] - p [i - 1]);
            s += sum;
            s2 += sum * sum;
        }
        
        s /= permutations.length;
        s2 /= permutations.length;
        
        System.out.println(s);
        System.out.println(s2);
        System.out.println(s2 - s * s);
    }
}