#include <iostream>
using namespace std;
const int mod = 1000000007;
int n, a[85], x[85][85], y[85][85], z[85][85]; long long b;
int main() {
	cin >> n >> b; b--;
	for (int i = 0; i < n; i++) {
		cin >> a[i];
		x[i][i] = a[i];
		for (int j = 0; j <= i; j++) y[j][i] = a[i];
	}
	while (b) {
		if (b & 1) {
			for (int i = 0; i < n; i++) {
				for (int j = i; j < n; j++) {
					z[i][j] = 0;
					for (int k = i; k <= j; k++) {
						z[i][j] = (z[i][j] + 1LL * x[i][k] * y[k][j]) % mod;
					}
				}
			}
			for (int i = 0; i < n; i++) {
				for (int j = i; j < n; j++) {
					x[i][j] = z[i][j];
				}
			}
		}
		for (int i = 0; i < n; i++) {
			for (int j = i; j < n; j++) {
				z[i][j] = 0;
				for (int k = i; k <= j; k++) {
					z[i][j] = (z[i][j] + 1LL * y[i][k] * y[k][j]) % mod;
				}
			}
		}
		for (int i = 0; i < n; i++) {
			for (int j = i; j < n; j++) {
				y[i][j] = 1LL * z[i][j];
			}
		}
		b >>= 1;
	}
	int ret = 0;
	for (int i = 0; i < n; i++) {
		for (int j = i + 1; j < n; j++) {
			ret = (ret + x[i][j]) % mod;
		}
	}
	cout << ret << '\n';
	return 0;
}