#include<bits/stdc++.h>
using namespace std;
#define cs const
#define re register
#define pb push_back
#define pii pair<int,int>
#define ll long long
#define fi first
#define se second
#define bg begin
cs int RLEN=1<<22|1;
char ibuf[RLEN],*ib,*ob;
inline char gc(){
    (ib==ob)&&(ob=(ib=ibuf)+fread(ibuf,1,RLEN,stdin));
    return (ib==ob)?EOF:*ib++;
}
inline int read(){
	char ch=gc();
	int res=0;bool f=1;
	while(!isdigit(ch))f^=ch=='-',ch=gc();
	while(isdigit(ch))res=(res+(res<<2)<<1)+(ch^48),ch=gc();
	return f?res:-res;
}
template<typename tp>inline void chemx(tp &a,tp b){(a<b)?(a=b):0;}
template<typename tp>inline void chemn(tp &a,tp b){(a>b)?(a=b):0;}
cs int mod=1e9+7;
inline int add(int a,int b){return (a+b)>=mod?(a+b-mod):(a+b);}
inline int dec(int a,int b){return (a<b)?(a-b+mod):(a-b);}
inline int mul(int a,int b){static ll r;r=(ll)a*b;return (r>=mod)?(r%mod):r;}
inline void Add(int &a,int b){a=(a+b)>=mod?(a+b-mod):(a+b);}
inline void Dec(int &a,int b){a=(a<b)?(a-b+mod):(a-b);}
inline void Mul(int &a,int b){static ll r;r=(ll)a*b;a=(r>=mod)?(r%mod):r;}
inline int ksm(int a,int b,int res=1){for(;b;b>>=1,Mul(a,a))(b&1)&&(Mul(res,a),1);return res;}
inline int Inv(int x){return ksm(x,mod-2);}
inline int fix(ll x){x%=mod;return (x<0)?x+mod:x;}

cs int N=77;

int f[N][N][N],g[N][N][N];
int n,t[1005];
void solve(){
	n=read();int ans=0;
	for(int i=1;i<=n;i++)t[i]=read();
	f[76][76][76]=1;
	for(int ii=1;ii<=n;ii++){
		memcpy(g,f,sizeof(f));
		memset(f,0,sizeof(f));
		for(int i=1;i<=76;i++)
		for(int j=i;j<=76;j++)
		for(int k=j;k<=76;k++)if(g[i][j][k]){
		//	cout<<i<<" "<<j<<" "<<k<<" "<<g[i][j][k]<<'\n';
			int i1=min(i+t[ii]-t[ii-1],76);
			int j1=min(j+t[ii]-t[ii-1],76);
			int k1=min(k+t[ii]-t[ii-1],76);
		//	cout<<i1<<" "<<j1<<" "<<k1<<'\n';
			{
				Add(f[i1][j1][k1],g[i][j][k]);
			}
		//	cout<<"ok1\n";
			{
				if(t[ii-1]-i+20>=t[ii]||t[ii-1]-k+75>=t[ii]){
					
					Add(f[i1][j1][k1],g[i][j][k]);
				}
				else{
					Add(f[1][i1][j],g[i][j][k]);
				//	cout<<n<<" "<<i<<'\n';
					Add(ans,mul(g[i][j][k],ksm(2,n-ii)));
				}
			}
	//		cout<<"ok2\n";
		}
	}
	cout<<mul(ans,2)<<'\n';
}

int main(){
	#ifdef Stargazer
	freopen("1.in","r",stdin);
	#endif
	int T=1;
	while(T--)solve();
}