#include<bits/stdc++.h>
#define sqr(x) ((x)*(x))
#define ll long long
#define ull unsigned long long
#define ui unsigned int
#define ld long double
#define vi vector<int>
#define HEAP(...) priority_queue<__VA_ARGS__ >
#define heap(...) priority_queue<__VA_ARGS__,vector<__VA_ARGS__ >,greater<__VA_ARGS__ > > 
#define pii pair<int,int> 
#define pb push_back
#define mp make_pair
#define debuge cerr<<"isok"<<endl
#define debug(x) cerr<<#x<<"="<<x<<endl
#define dprintf(...) fprintf(stderr,__VA_ARGS__)
#define SS second
#define FF first
#define ls (k<<1)
#define rs (k<<1|1)
#define clr(a,x) memset(a,x,sizeof(a))
#define cpy(a,x) memcpy(a,x,sizeof(a))
#define file(x) freopen(x".in","r",stdin),freopen(x".out","w",stdout)
#define SZ(x) ((int)x.size())
using namespace std;
template<class T> inline void gmin(T &x,const T &y){if(x>y) x=y;}
template<class T> inline void gmax(T &x,const T &y){if(x<y) x=y;}
const int BufferSize=1<<16;
char buffer[BufferSize],*Bufferhead,*Buffertail;
bool Terminal;
inline char Getchar(){
	if(Bufferhead==Buffertail){
		int l=fread(buffer,1,BufferSize,stdin);
		if(!l){Terminal=1;return 0;}
		Buffertail=(Bufferhead=buffer)+l;
	}
	return *Bufferhead++;
}
template<class T>inline bool read(T &x){
	x=0;char c=Getchar(),rev=0;
	while(c<'0'||c>'9'){rev|=c=='-';c=Getchar();if(Terminal)return 0;}
	while(c>='0'&&c<='9') x=x*10+c-'0',c=Getchar();
	if(c=='.'){
		c=Getchar();double t=0.1;
		while(c>='0'&&c<='9') x=x+(c-'0')*t,c=Getchar(),t=t/10;
	}
	x=rev?-x:x;
	return 1;
}
template<class T1,class T2> inline bool read(T1 &x,T2 &y){return read(x)&read(y);}
template<class T1,class T2,class T3> inline bool read(T1 &x,T2 &y,T3 &z){return read(x)&read(y)&read(z);}
template<class T1,class T2,class T3,class T4> inline bool read(T1 &x,T2 &y,T3 &z,T4 &w){return read(x)&read(y)&read(z)&read(w);}
inline bool reads(char *x){
	char c=Getchar();
	while(c<33||c>126){c=Getchar();if(Terminal)return 0;}
	while(c>=33&&c<=126) (*x++)=c,c=Getchar();
	*x=0;return 1;
}
template<class T>inline void print(T x,const char c='\n'){
	if(!x){putchar('0');putchar(c);return;}
	if(x<0) putchar('-'),x=-x;
	int m=0,a[20];
	while(x) a[m++]=x%10,x/=10;
	while(m--) putchar(a[m]+'0');
	putchar(c);
}
//--------------------------------head---------------------------------------------

const int inf=0x3f3f3f3f;
const int N=200005,M=100005,mod=1e9+7;
template<class T,class S> inline void ch(T &x,const S y){x=(x+y)%mod;}
inline int exp(int x,int y,const int mod=::mod){
	int ans=1;
	while(y){
		if(y&1) ans=(ll)ans*x%mod;
		x=(ll)x*x%mod;y>>=1;
	}return ans;
}

int n,tot,mx,pw[N],dep[N],num[N],bnd[N],f[N][20],dp[N][2];
vi g[N],v[N];

inline bool cmp(const int &x,const int &y){return num[x]<num[y];}
inline int lca(int x,int y){
	if(dep[x]>dep[y]) swap(x,y);
	for(int i=0,t=dep[y]-dep[x];i<18;i++)
		if(t&(1<<i)) y=f[y][i];
	if(x==y) return x;
	for(int i=17;~i;i--)
		if(f[x][i]!=f[y][i]) x=f[x][i],y=f[y][i];
	return f[x][0];
}
inline void dfs(int x){
	num[x]=++tot;
	for(int y:g[x])
		dfs(y);
	bnd[x]=tot;
}
inline int solve(int x){
	if(!SZ(g[x])){dp[x][0]=dp[x][1]=1;return 1;}
	int s0=1,s1=0,cnt=0;
	for(int y:g[x]){
		cnt+=solve(y);
		ch(s1,(ll)dp[y][1]*exp(dp[y][0],mod-2));
		s0=(ll)s0*dp[y][0]%mod;
	}
	dp[x][1]=(ll)s0*s1%mod;
	dp[x][0]=(pw[cnt]-dp[x][1]+mod)%mod;
	return cnt;
}

int main(){
#ifdef rqgao2014
	assert(freopen("input.txt","r",stdin));
#endif
	read(n);pw[0]=1;
	for(int i=1;i<=n;i++) pw[i]=pw[i-1]*2%mod;
	v[0].pb(0);
	for(int i=1;i<=n;i++){
		int x;read(x);
		f[i][0]=x;
		g[x].pb(i);dep[i]=dep[x]+1;
		v[dep[i]].pb(i);gmax(mx,dep[i]);
	}
	dfs(0);
	for(int i=0;i<=n;i++) g[i].clear();
	for(int j=1;j<18;j++)
		for(int i=0;i<=n;i++)
			f[i][j]=f[f[i][j-1]][j-1];
	int ans=0;
	for(int D=0;D<=mx;D++){
		static int b[N<<1],fa[N];
		int m=SZ(v[D]);
		for(int i=1;i<=m;i++) b[i]=v[D][i-1];
		sort(b+1,b+m+1,cmp);
		for(int i=1,t=m;i<t;i++) b[++m]=lca(b[i],b[i+1]);
		sort(b+1,b+m+1,cmp);
		m=unique(b+1,b+m+1)-b-1;
		for(int i=2,j=1;i<=m;i++){
			while(j&&num[b[i]]>bnd[b[j]]) j=fa[j];
//			dprintf("%d %d\n",j,i);
			g[j].pb(i);fa[i]=j;j=i;
		}
		int cnt=solve(1);
//		debug(dp[1][1]);
		ch(ans,(ll)dp[1][1]*pw[n+1-cnt]);
		for(int i=1;i<=m;i++)
			g[i].clear();
	}
	printf("%d\n",ans);
	return 0;
}

Measured memory_bytes: 48640