#include<iostream>
#include<cstdio>
#define N 2000
#define mod 1000000007
using namespace std;
int read()
{
    char c=0;
    int sum=0;
    while (c<'0'||c>'9') c=getchar();
    while ('0'<=c&&c<='9') sum=sum*10+c-'0',c=getchar();
    return sum;
}
int MD(int x)
{
    return (x>=mod)?x-mod:x;
}
void Adder(int &x,int d)
{
    x+=d;
    if (x>=mod) x-=mod;
    return;
}
int n,res,res2,ans,w[N+1],dp[N+1][N+1][2];
int main()
{
    while (scanf("%d",&n)!=EOF)
    {
		ans=0;
		for (int i=1;i<=n;++i) w[i]=read();
		for (int i=1;i<=n;++i)
			for (int j=1;j<=n;++j)
				dp[i][j][0]=dp[i][j][1]=0;
		for (int i=1;i<=n;++i)
		{
			Adder(dp[1][i][1],1);
			for (int j=1;j<=n;++j)
			{
				if (i<j) Adder(dp[2][j][0],1);
				else Adder(dp[2][j][1],w[i]);
			}
		}
		for (int i=3;i<=n;++i)
		{
			res=0;
			for (int j=1;j<=n;++j) Adder(dp[i][j][0],1ll*res*w[j]%mod),Adder(res,dp[i-1][j][0]);
			res=0;
			for (int j=n;j>=1;--j) Adder(res,1ll*dp[i-1][j][1]*w[j]%mod),Adder(dp[i][j][1],res);
			res=res2=0;
			for (int j=n;j>=1;--j)
			{
				Adder(res,1ll*dp[i-1][j][0]*w[j]%mod*w[j]%mod),Adder(res2,1ll*dp[i-1][j][0]*w[j]%mod);
				if (i==n) Adder(ans,res2);
				Adder(dp[i][j][1],res);
			}
			res=0;
			for (int j=1;j<=n;++j) Adder(dp[i][j][0],1ll*res*w[j]%mod),Adder(res,1ll*MD(1ll*dp[i-2][j][0]*w[j]%mod+dp[i-2][j][1])*j%mod);
			res=0;
			for (int j=n;j>=1;--j) Adder(res,1ll*MD(1ll*dp[i-2][j][0]*w[j]%mod+dp[i-2][j][1])*w[j]%mod),Adder(dp[i][j][0],1ll*res*(j-1)%mod);
		}
		for (int i=1;i<=n;++i) Adder(ans,dp[n][i][0]),Adder(ans,1ll*dp[n-1][i][1]*i%mod);
		printf("%d\n",ans);
    }
    return 0;
}