/*
f_{i,0,k} <=k,<=k,unlimit
0:=\sum_{l=k}^n f_{i,0,l}
1:=(k-1)*\sum_{l=k}^n f_{i,0,l}
2:=(k-1)*(k-1)*\sum_{l=k}^n f_{i,0,l}
2:i->j min(i,j-1)*min(i,j-1)

2->1 2
1->0 2
0->0 1 2

2->2
<=k <=k unlimit
<l s limit=k
>=l g limit=l-1
1->2
j k l
j>=k
j<l
\sum_{j=1}^{l-1}f_{i,1,j}*j
*/
#pragma GCC optimize("Ofast")
#include<bits/stdc++.h>
using namespace std;const int N=2010,mod=1e9+7;int add(int x,int y){return (x+=y)>=mod?x-mod:x;}int f[N][3][N],g[N],s,n,m,a[N],ans;void solve(){g[n+1]=ans=0;for(int i=1;i<=n;++i)scanf("%d",&a[i]);for(int i=0;i<=n+1;++i)for(int j=0;j<3;++j)memset(f[i][j],0,(n+2)<<2);
for(int j=1;j<=n;++j)f[1][0][j]=a[j],f[1][1][j]=(j-1ll)*a[j]%mod,f[1][2][j]=(j-1ll)*(j-1)*a[j]%mod;for(int i=1;i<n-2;++i){for(int j=1;j<3;++j)for(int k=1;k<=n;++k)f[i+1][j-1][k]=f[i][j][k];
for(int k=n;k;--k)g[k]=add(g[k+1],f[i][0][k]);s=0;for(int k=1;k<=n;++k)f[i+1][0][k]=add(f[i+1][0][k],g[k]),f[i+1][1][k]=(f[i+1][1][k]+(k-1ll)*g[k])%mod,f[i+1][2][k]=(s+(k-1ll)*(k-1ll)*g[k])%mod,s=(s+1ll*k*k*f[i][0][k])%mod;
/*for(int k=1;k<=n;++k)g[k]=add(g[k-1],f[i][2][k]);*/s=0;for(int k=1;k<=n;++k)f[i+1][2][k]=add(f[i+1][2][k],s),s=(s+1ll*k*f[i][1][k]+f[i][2][k])%mod;
for(int j=0;j<3;++j)for(int k=1;k<=n;++k)f[i+1][j][k]=1ll*f[i+1][j][k]*a[k]%mod;}for(int i=1;i<=n;++i)ans=(ans+f[n-2][2][i]+1ll*i*f[n-2][1][i]+1ll*i*i*f[n-2][0][i])%mod;printf("%d\n",ans);}int main(){for(;scanf("%d",&n)!=EOF;)solve();return 0;}