using System;

public class Hello
{
    static void Main()
    {
        var n = int.Parse(Console.ReadLine().Trim());
        string[] line = Console.ReadLine().Trim().Split(' ');
        var a = Array.ConvertAll(line, long.Parse);
        getAns(n, a);
    }
    static void getAns(int n, long[] a)
    {
        var sum = 0L;
        for (long i = 0; i < n / 2; i++)
        {
            sum += (i + 1) * (n - i) * (a[i] + a[n - 1 - i]);
        }
        if (n % 2 == 1) sum += (n / 2 + 1) * (n - n / 2) * a[n / 2];
        Console.WriteLine(sum);
    }
}