#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

typedef int _loop_int;
#define REP(i,n) for(_loop_int i=0;i<(_loop_int)(n);++i)
#define FOR(i,a,b) for(_loop_int i=(_loop_int)(a);i<(_loop_int)(b);++i)
#define FORR(i,a,b) for(_loop_int i=(_loop_int)(b)-1;i>=(_loop_int)(a);--i)

#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define DEBUG_VEC(v) cout<<#v<<":";REP(i,v.size())cout<<" "<<v[i];cout<<endl
#define ALL(a) (a).begin(),(a).end()

#define CHMIN(a,b) a=min((a),(b))
#define CHMAX(a,b) a=max((a),(b))

// mod
const ll MOD = 1000000007ll;
#define FIX(a) ((a)%MOD+MOD)%MOD

// floating
typedef double Real;
const Real EPS = 1e-11;
#define EQ0(x) (abs(x)<EPS)
#define EQ(a,b) (abs(a-b)<EPS)
typedef complex<Real> P;

ll n,c;
ll a[85];

typedef vector<vl> mat;

mat mul(mat &a,mat &b){
  int n = a.size();
  mat ret(n,vl(n,0));
  REP(k,n)REP(i,n)REP(j,n)ret[i][j] = (ret[i][j] + a[i][k]*b[k][j]%MOD)%MOD;
  return ret;
}

ll mypow(ll a,ll b){
  b %= (MOD-1);
  ll r = 1;
  while(b){
    if(b&1)r=r*a%MOD;
    a=a*a%MOD;
    b>>=1;
  }
  return r;
}

int main(){
  scanf("%lld%lld",&n,&c);
  REP(i,n)scanf("%lld",a+i);
  mat A(n,vl(n,0));
  REP(i,n)REP(j,i+1)A[i][j] = a[i];
  mat I(n,vl(n,0));
  REP(i,n)I[i][i]=1;
  mat B = I;
  ll k = c;
  --c;
  while(c){
    if(c&1) B=mul(A,B);
    A=mul(A,A);
    c>>=1;
  }
  ll sum = 0;
  REP(i,n)REP(j,n)sum = (sum + B[i][j]*a[j]%MOD)%MOD;
  REP(i,n)sum = (sum-mypow(a[i],k)+MOD)%MOD;
  printf("%lld\n",sum);
  return 0;
}