#include <bits/stdc++.h>
#define S second
#define TT int T;cin >> T;while(T--)
#define F first
#define ll long long
#define ld long double
#define ue(times ,x) for(int _i = 0; _i < times; _i++){int _u, _v;cin >> _u >> _v;x[_u].push_back(_v);x[_v].push_back(_u);}
#define de(times ,x) for(int _i = 0; _i < times; _i++){int _u, _v;cin >> _u >> _v;x[_u].push_back(_v);}
#define pb push_back
#define SRT(v) sort(v.begin(), v.end())
#define SRT1(v) sort(v.begin()+1, v.end())
#define TLE ios_base::sync_with_stdio(false);cin.tie(NULL)
#define All(v) v.begin(),v.end()
#define INF 223372036854775807
typedef __int128 lll;
using namespace std;
const ll MAXN = 1e5+5;
ll MOD = 1000000007;

ll fast_pow(ll base, ll exp, ll mod = MOD) {
    ll res = 1; base %= mod;
    while (exp > 0) {
        if (exp & 1) res = (ll)((__int128)res * base % mod);
        base = (ll)((__int128)base * base % mod);
        exp >>= 1;
    }
    return res;
}

int main() 
{
    TLE;
    int t ; cin >> t;
    for (int g = 1; g <= t ; g++)
    {
        ll n; cin >> n;
        ll sum = 0 ;
        for ( int i = 1; i <= n; i++ ){
            ll x; cin >> x; 
            sum = (sum + x) % MOD ;  
        }
        ll ans = sum * fast_pow(2,n-1) % MOD ;
        cout << "Case " << g << ": " << ans << '\n';
    }
    return 0;
}