#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#define popcount __builtin_popcount
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;
const ll MOD=1e9+7;
vector<vector<ll>> matrixmul(int l, int m, int n, vector<vector<ll>> a, vector<vector<ll>> b){
	vector<vector<ll>> c(l, vector<ll>(n));
	for(int i=0; i<l; i++){
		for(int j=0; j<n; j++){
			for(int k=0; k<m; k++){
				(c[i][j]+=a[i][k]*b[k][j])%=MOD;
			}
		}
	}
	return c;
}
vector<vector<ll>> matrixpow(int n, vector<vector<ll>> a, ll k){
	vector<vector<ll>> ap=a, ans(n, vector<ll>(n));
	for(int i=0; i<n; i++) ans[i][i]=1;
	while(k){
		if(k&1) ans=matrixmul(n, n, n, ap, ans);
		ap=matrixmul(n, n, n, ap, ap);
		k>>=1;
	}
	return ans;
}
ll powmod(ll a, ll k){
    ll ap=a, ans=1;
    while(k){
        if(k&1){
            ans*=ap;
            ans%=MOD;
        }
        ap=ap*ap;
        ap%=MOD;
        k>>=1;
    }
    return ans;
}
int main()
{
	int n;
	ll c;
	cin>>n>>c;
	ll a[88];
	for(int i=0; i<n; i++) cin>>a[i];
	vector<vector<ll>> mat(n, vector<ll>(n));
	for(int i=0; i<n; i++) for(int j=0; j<=i; j++) mat[i][j]=a[i];
	auto mp=matrixpow(n, mat, c-1);
	ll ans=0;
	for(int i=0; i<n; i++) for(int j=0; j<n; j++) (ans+=mp[i][j]*a[j])%=MOD;
	for(int i=0; i<n; i++) (ans+=MOD-powmod(a[i], c))%=MOD;
	cout<<ans<<endl;
	return 0;
}