#include <bits/stdc++.h>
using namespace std;

const int64_t MOD = 1e9+7;
void add(int64_t& a, int64_t b){
    a = (a+b) % MOD;
}
void mul(int64_t& a, int64_t b){
    a = a*b % MOD;
}

int64_t power_mod(int64_t num, int64_t power){
    int64_t prod = 1;
    num %= MOD;
    while(power > 0){
        if(power&1) prod = prod * num % MOD;
        num = num * num % MOD;
        power >>= 1;
    }
    return prod;
}

int64_t extgcd(int64_t a, int64_t b, int64_t& x, int64_t& y){
    int64_t d = a;
    if(b != 0){
        d = extgcd(b, a%b, y, x);
        y -= (a/b) * x;
    }else{
        x = 1; y = 0;
    }
    return d;
}

int64_t inv_mod(int64_t a){
    int64_t x, y;
    extgcd(a, MOD, x, y);
    return (MOD + x%MOD) % MOD;
}

int main(){
    int N, K;
    cin >> N >> K;
    vector<int64_t> A(N);
    for(int i=0; i<N; i++) cin >> A[i];

    vector<int64_t> F(N, 1);
    for(int i=1; i<N; i++){
        F[i] = F[i-1] * (i+K) % MOD * inv_mod(i) % MOD;
    }

    int64_t ans = 0;
    for(int i=0; i<N; i++){
        int64_t res = A[i];
        mul(res, F[i]);
        mul(res, F[N-1-i]);
        add(ans, res);
    }
    cout << ans << endl;
    return 0;
}