#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
using ll = long long;

constexpr int P = 1000000007;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    int n, k;
    cin >> n >> k;

    vector<int> x(n), y(n);
    x[1] = 1;
    y[0] = 1;
    y[1] = k + 1;
    for (int i = 2; i < n; i++) {
        y[i] = (ll)y[i - 1] * (x[i] = P - (P / i * (ll)x[P % i] % P)) % P * (k + i) % P;
    }

    ll r = 0;
    for (int i = 0; i < n; i++) {
        int a;
        cin >> a;

        r += (ll)a * y[i] % P * y[n - 1 - i] % P;
    }
    r %= P;

    cout << r << endl;

    return 0;
}