#include<bits/stdc++.h>
typedef long long ll;
const int N=43,E=800,C=37357,M=1e9+7;
int n,a[N],fac[E],invf[E],cnt,siz[C],f[C][E],g[N][N],ans;
struct data{int a,c;};
std::vector<data>b[C],bb;
struct hash_table{
	int head[C],k;
	struct node{ll a;int p,nxt;}h[C];
	inline int&operator[](const std::vector<data>&b){
		ll a=0;
		for(data dt:b)for(int j=0;j<dt.c;j++)a=a<<dt.a|1;
		int aa=a%C;
		for(int i=head[aa];i;i=h[i].nxt)if(h[i].a==a)return h[i].p;
		h[++k]=(node){a,0,head[aa]},head[aa]=k;
		return h[k].p;
	}
}h;
inline int Pow(int a,int m){int s=1;for(;m;m>>=1)m&1?s=(ll)s*a%M:0,a=(ll)a*a%M;return s;}
inline int A(int n,int m){return(ll)fac[n]*invf[n-m]%M;}
void Dfs(int s,int l,int c){
	if(s==n){++cnt,h[bb]=cnt,b[cnt]=bb,siz[cnt]=n-c;return;}
	if(l&&s+l<=n){
		++bb.back().c;
		Dfs(s+l,l,c+1);
		--bb.back().c;
	}
	for(int j=l+1;s+j<=n;j++){
		bb.push_back((data){j,1});
		Dfs(s+j,j,c+1);
		bb.pop_back();
	}
}
inline void Dp(int&a,int b,int c){a=((ll)b*c+a)%M;}
int main(){
	scanf("%d",&n);
	fac[0]=1;
	for(int i=1;i<=n*(n-1)/2;i++)fac[i]=(ll)fac[i-1]*i%M;
	invf[n*(n-1)/2]=Pow(fac[n*(n-1)/2],M-2);
	for(int i=n*(n-1)/2;i;i--)invf[i-1]=(ll)invf[i]*i%M;
	for(int i=1;i<n;i++)scanf("%d",a+i);
	Dfs(0,0,0);
	for(int i=1;i<cnt;i++){
		for(int j=0;j<b[i].size();j++)
			for(int k=j+(b[i][j].c==1);k<b[i].size();k++){
				bb.clear();
				for(int l=0;l<b[i].size();l++)
					if(b[i][l].c-(j==l)-(k==l))
						bb.push_back((data){b[i][l].a,b[i][l].c-(j==l)-(k==l)});
				for(int l=0;l<bb.size();l++)
					if(bb[l].a>=b[i][j].a+b[i][k].a){
						if(bb[l].a==b[i][j].a+b[i][k].a)++bb[l].c;
						else bb.insert(bb.begin()+l,(data){b[i][j].a+b[i][k].a,1});
						goto Brk;
					}
				bb.push_back((data){b[i][j].a+b[i][k].a,1});
			  Brk:;
				g[j][k]=h[bb];
			}
		if(i==1)f[i][0]=1;
		for(int l=a[siz[i]+1]-a[siz[i]]-1;l<=n*(n-1)/2;l++){
			if(!f[i][l])continue;
			for(int j=0;j<b[i].size();j++){
				if(b[i][j].c>1)
					Dp(f[g[j][j]][l-(a[siz[i]+1]-a[siz[i]]-1)+(b[i][j].a*b[i][j].a-1)],f[i][l],b[i][j].a*b[i][j].a*b[i][j].c*(b[i][j].c-1)/2*(ll)A(l,a[siz[i]+1]-a[siz[i]]-1)%M);
				for(int k=j+1;k<b[i].size();k++)
					Dp(f[g[j][k]][l-(a[siz[i]+1]-a[siz[i]]-1)+(b[i][j].a*b[i][k].a-1)],f[i][l],b[i][j].a*b[i][k].a*b[i][j].c*b[i][k].c*(ll)A(l,a[siz[i]+1]-a[siz[i]]-1)%M);
			}
		}
	}
	ans=(ll)f[cnt][n*(n-1)/2-a[n-1]]*A(n*(n-1)/2-a[n-1],n*(n-1)/2-a[n-1])%M;
	printf("%d\n",ans);
	return 0;
}