#pragma GCC optimize ("O2")
#pragma GCC target ("avx2")
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for(int i = 0; i < (n); i++)
#define rep1(i, n) for(int i = 1; i <= (n); i++)
#define co(x) cout << (x) << "\n"
#define cosp(x) cout << (x) << " "
#define ce(x) cerr << (x) << "\n"
#define cesp(x) cerr << (x) << " "
#define pb push_back
#define mp make_pair
#define chmin(x, y) x = min(x, y)
#define chmax(x, y) x = max(x, y)
#define Would
#define you
#define please

const int mod = 1e9 + 7;
const int IMAX = 100010;
constexpr ll modpow(ll A, ll B) {
	ll kotae = 1;
	while (B > 0) {
		if (B & 1) kotae = kotae * A % mod;
		A = A * A % mod;
		B >>= 1;
	}
	return kotae;
}
class unko {
public:
	int fac[IMAX + 1], ifac[IMAX + 1], inv[IMAX + 1];
	unko() : fac(), ifac(), inv() {
		fac[0] = 1;
		rep1(i, IMAX) fac[i] = ll(fac[i - 1]) * i % mod;
		ifac[IMAX] = modpow(fac[IMAX], mod - 2);
		for (int i = IMAX; i > 0; i--) ifac[i - 1] = ll(ifac[i]) * i % mod;
		inv[0] = 1;
		rep1(i, IMAX) inv[i] = ll(ifac[i]) * fac[i - 1] % mod;
	}
	int comb(int A, int B) {
		return ll(fac[A]) * ifac[B] % mod * ifac[A - B] % mod;
	}
} f;

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


	int N, K;
	cin >> N >> K;

	ll are[100001];
	are[0] = 1;
	rep(i, N) {
		are[i + 1] = are[i] * (K + i + 1) % mod * f.inv[i + 1] % mod;
	}

	ll kotae = 0;

	rep(i, N) {
		ll a;
		cin >> a;
		kotae += a * are[i] % mod * are[N - i - 1] % mod;
	}

	co(kotae% mod);



	Would you please return 0;
}