// 
#include<bits/stdc++.h>
#define ll long long
#define ld double
#define PII pair<int,int>
#define PLI pair<ll,int>
#define fi first
#define se second
#define iter set<PII>::iterator
using namespace std;
const int N=2005,M=55,Mod=1e9+7;
int n,a[N],f[M][N],b[N],fac[N],inv[N],ifac[N],ipw2[N],ans=1;
int C(int x,int y){return (ll)fac[x]*ifac[y]%Mod*ifac[x-y]%Mod;}
int ksm(int x,int y=Mod-2)
{
	int z=1;
	while(y){if(y&1)z=(ll)z*x%Mod;x=(ll)x*x%Mod;y>>=1;}
	return z;
}
int main()
{
	#ifndef ONLINE_JUDGE
	freopen(".in","r",stdin);
	freopen(".out","w",stdout);
	#endif
	
	fac[0]=ifac[0]=inv[0]=inv[1]=ipw2[0]=1;
	for(int i=2;i<N;i++)inv[i]=(ll)(Mod-Mod/i)*inv[Mod%i]%Mod;
	for(int i=1;i<N;i++)fac[i]=(ll)fac[i-1]*i%Mod,ifac[i]=(ll)ifac[i-1]*inv[i]%Mod,ipw2[i]=(ll)ipw2[i-1]*inv[2]%Mod;
	scanf("%d",&n);
	for(int i=1;i<=n;i++)scanf("%d",&a[i]),++b[a[i]];
	for(int i=49;~i;i--)b[i]+=b[i+1];
	for(int i=0;i<n;i++)
	{
		for(int j=0;j<=i;j++)
		{
			(f[0][i]+=(ll)(j&1?Mod-1:1)*C(n,j)%Mod*ksm(i+1-j,n)%Mod)%=Mod;
		}
		// printf("%d ",f[0][i]);
	}
	// puts("");
	for(int i=n-1;i;i--)(f[0][i]+=Mod-f[0][i-1])%=Mod;
	for(int i=1;i<=50;i++)
	{
		for(int j=0;j<=n*2;j++)
		{
			for(int k=0;k<=b[i];k++)
			{
				(f[i][(j+k)/2]+=(ll)f[i-1][j]*C(b[i],k)%Mod*ipw2[b[i]]%Mod)%=Mod;
				// printf("%d %d %d\n",i,j,k),fflush(stdout);
			}
			// if(f[i-1][j])printf("%d %d %d\n",i-1,j,4ll*f[i-1][j]%Mod);
		}
	}
	for(int i=50,sum=(ll)(Mod-1)*ifac[n]%Mod;~i;i--)
	{
		ans=(ans+(ll)sum*f[i][0]%Mod*(b[i]-b[i+1]))%Mod;
		sum=(ll)sum*ipw2[b[i]]%Mod;
	}
	printf("%d\n",ans);
    
	cerr<<1.0*clock()/CLOCKS_PER_SEC<<'\n';
}
/*
4
1 2 1 3
*/