#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=a;i>=b;i--)
#define fore(i,a) for(auto &i:a)
#pragma GCC optimize ("-O3")
using namespace std; void _main(); int main() { cin.tie(0); ios::sync_with_stdio(false); _main(); }
//---------------------------------------------------------------------------------------------------
template<int MOD> struct ModInt {
    static const int Mod = MOD; unsigned x; ModInt() : x(0) { }
    ModInt(signed sig) { x = sig < 0 ? sig % MOD + MOD : sig % MOD; }
    ModInt(signed long long sig) { x = sig < 0 ? sig % MOD + MOD : sig % MOD; }
    int get() const { return (int)x; }
    ModInt &operator+=(ModInt that) { if ((x += that.x) >= MOD) x -= MOD; return *this; }
    ModInt &operator-=(ModInt that) { if ((x += MOD - that.x) >= MOD) x -= MOD; return *this; }
    ModInt &operator*=(ModInt that) { x = (unsigned long long)x * that.x % MOD; return *this; }
    ModInt &operator/=(ModInt that) { return *this *= that.inverse(); }
    ModInt operator+(ModInt that) const { return ModInt(*this) += that; }
    ModInt operator-(ModInt that) const { return ModInt(*this) -= that; }
    ModInt operator*(ModInt that) const { return ModInt(*this) *= that; }
    ModInt operator/(ModInt that) const { return ModInt(*this) /= that; }
    ModInt inverse() const { long long a = x, b = MOD, u = 1, v = 0;
        while (b) { long long t = a / b; a -= t * b; std::swap(a, b); u -= t * v; std::swap(u, v); }
        return ModInt(u); }
    bool operator==(ModInt that) const { return x == that.x; }
    bool operator!=(ModInt that) const { return x != that.x; }
    ModInt operator-() const { ModInt t; t.x = x == 0 ? 0 : Mod - x; return t; }
};
template<int MOD> ostream& operator<<(ostream& st, const ModInt<MOD> a) { st << a.get(); return st; };
template<int MOD> ModInt<MOD> operator^(ModInt<MOD> a, unsigned long long k) {
    ModInt<MOD> r = 1; while (k) { if (k & 1) r *= a; a *= a; k >>= 1; } return r; }
template<typename T, int FAC_MAX> struct Comb { vector<T> fac, ifac;
    Comb() {fac.resize(FAC_MAX, 1); ifac.resize(FAC_MAX, 1);rep(i, 1, FAC_MAX) fac[i] = fac[i - 1] * i;
        rep(i, 1, FAC_MAX) ifac[i] = T(1) / fac[i];}
    T aPb(int a, int b) { if (b < 0 || a < b) return T(0); return fac[a] * ifac[a - b]; }
    T aCb(int a, int b) { if (b < 0 || a < b) return T(0); return fac[a] * ifac[a - b] * ifac[b]; }
    T nHk(int n, int k) { if (n == 0 && k == 0) return T(1); if (n <= 0 || k < 0) return 0;
        return aCb(n + k - 1, k); }}; // nHk = (n+k-1)Ck
typedef ModInt<1000000007> mint;
/*---------------------------------------------------------------------------------------------------
　　　　　　　　　　　 ∧＿∧  
　　　　　 ∧＿∧ 　（´<_｀ ）　 Welcome to My Coding Space!
　　　　 （ ´_ゝ`）　/　 ⌒i     
　　　　／　　　＼　 　  |　|     
　　　 /　　 /￣￣￣￣/　　|  
　 ＿_(__ﾆつ/　    ＿/ .| .|＿＿＿＿  
　 　　　＼/＿＿＿＿/　（u　⊃  
---------------------------------------------------------------------------------------------------*/
 



int N; vector<int> child[201010];
//---------------------------------------------------------------------------------------------------
int dpt[201010];
void pre(int cu) {
    fore(c, child[cu]) {
        dpt[c] = dpt[cu] + 1;
        pre(c);
    }
}
//---------------------------------------------------------------------------------------------------
deque<vector<mint>> dp[201010];
void dfs(int cu) {
    int ma = 0;
    fore(c, child[cu]) {
        dfs(c);

        if (dp[cu].size() < dp[c].size()) swap(dp[cu], dp[c]);

        deque<vector<mint>> memo;
        int n = dp[c].size();
        ma = max(ma, n);
        while(!dp[c].empty()) {
            auto a = dp[cu].front(); dp[cu].pop_front();
            auto b = dp[c].front(); dp[c].pop_front();

            vector<mint> v = { 0, 0, 0 };
            rep(j, 0, 3) rep(k, 0, 3) v[min(2, j + k)] += a[j] * b[k];
            memo.push_front(v);
        }
        while (!memo.empty()) {
            dp[cu].push_front(memo.front());
            memo.pop_front();
        }
    }
    
    /*deque<vector<mint>> pd;
    while (!dp[cu].empty()) {
        auto v = dp[cu].front();
        dp[cu].pop_front();
        v[0] += v[2];
        v[2] = 0;
        pd.push_back(v);
    }
    swap(dp[cu], pd);*/

    deque<vector<mint>> mem;
    rep(i, 0, ma) {
        auto v = dp[cu].front();
        dp[cu].pop_front();
        v[0] += v[2];
        v[2] = 0;
        mem.push_back(v);
    }
    while (!mem.empty()) {
        auto v = mem.back();
        mem.pop_back();
        dp[cu].push_front(v);
    }

    dp[cu].push_front({ 1, 1, 0 });
}
//---------------------------------------------------------------------------------------------------
void _main() {
    cin >> N;
    rep(i, 0, N) {
        int p; cin >> p;
        child[p].push_back(i + 1);
    }

    pre(0);
    map<int, int> cnt;
    rep(i, 0, N + 1) cnt[dpt[i]]++;

    dfs(0);

    mint ans = 0;
    int tim = 0;
    while(!dp[0].empty()) {
        auto a = dp[0].front(); dp[0].pop_front();
        ans += a[1] * (mint(2) ^ (N + 1 - cnt[tim]));
        tim++;
        //cout << a[1] << endl;
    }
    cout << ans << endl;
}


Measured memory_bytes: 214400