#include<bits/stdc++.h>
using namespace std;
using i64=long long;
constexpr i64 mod=1000000007;
int n;
i64 f[76][76][76],pw[1010],ans;
int main(){
   scanf("%d",&n);
   pw[0]=1;for(int i=1;i<=n;i++)pw[i]=pw[i-1]*2%mod;
   int lst=0;
   f[0][20][40]=1;
   for(int t;n--;){
      scanf("%d",&t);
      int d=t-lst;
      i64 g[76][76][76]{};
      for(int x=0;x<=75;x++)for(int y=x+20;y<=75;y++)for(int z=y+20;z<=75;z++){
         int a=max(x-d,0),b=max(y-d,0),c=max(z-d,0);
         if(a)(g[a][b][c]+=f[x][y][z]*2)%=mod;
         else(g[max(b,20)][max({c,b+20,40})][max({75,b+40,c+20})]+=f[x][y][z])%=mod,(g[0][20][40]+=f[x][y][z])%=mod,(ans+=f[x][y][z]*pw[n])%=mod;
      }
      memcpy(f,g,sizeof(g));
      lst=t;
   }
   printf("%lld",ans*2%mod);
   return 0;
}