#include <bits/stdc++.h> using namespace std; int MOD=1000000007; template<typename type=int> class Matrix{ public: vector<vector<type>> value; Matrix(vector<vector<type>> e){ value=e; } Matrix<type> operator * (Matrix a){ vector<vector<type>> ret(value.size(),vector<type>(a.value[0].size())); type temp; for(int i=value.size()-1;i>=0;i--){ for(int j=a.value[0].size()-1;j>=0;j--){ temp=0; for(int k=a.value.size()-1;k>=0;k--){ temp=(temp+value[i][k]*a.value[k][j])%MOD; } ret[i][j]=temp; } } return Matrix(ret); } Matrix<type> pow(long long p){ Matrix temp=value; Matrix ans=temp; bool flg=false; while(p>0){ if(p%2){ if(flg){ ans=ans*temp; }else{ flg=true; ans=temp; } } p=p/2; temp=temp*temp; } return ans; } }; long long pawf(long long a,long long n){ long long ans=1; long long temp=a%MOD; while(n>0){ if(n%2){ ans=(ans*temp)%MOD; } temp=(temp*temp)%MOD; n=n/2; } return ans; } int main(){ long long n,c; cin>>n>>c; Matrix<long long> b(vector<vector<long long>>(n,vector<long long>(1,1))); vector<vector<long long>> Av(n,vector<long long>(n,0)); vector<long long> a(n); for(int i=0;i<n;i++){ cin>>a[i]; } for(int i=0;i<n;i++){ for(int j=0;j<=i;j++){ Av[i][j]=a[j]%MOD; } } Matrix<long long> A(Av); Matrix<long long> p=A.pow(c); long long ans=(A.pow(c)*b).value[n-1][0]; for(int i=0;i<n;i++){ ans=ans-pawf(a[i],c); } while(ans<0)ans+=MOD; cout<<ans<<endl; }