import std.stdio, std.array, std.string, std.conv, std.algorithm;
import std.typecons, std.range, std.random, std.math, std.container;
import std.numeric, std.bigint, core.bitop;

immutable long MOD = 10^^9 + 7;

void main() {
    auto N = readln.chomp.to!int;
    auto A = readln.split.map!(to!long).array;

    long ans = 0;
    long pro = 1;
    long co = 2;
    foreach (i; 0..N-2) co = co * 3 % MOD;

    foreach (i, a; A) {
        pro = pro * a % MOD;
        (ans += pro * co) %= MOD;
        if (i + 2 == N) {
            co = co * powmod(2, MOD-2, MOD) % MOD;
        } else {
            co = co * powmod(3, MOD-2, MOD) % MOD;
        }
    }

    ans.writeln;
}

long powmod(long a, long x, long m) {
    long ret = 1;
    while (x) {
        if (x % 2) ret = ret * a % m;
        a = a * a % m;
        x /= 2;
    }
    return ret;
}