#line 1 "main.cpp"

/**
 * @title Template
 */

#include <iostream>
#include <algorithm>
#include <utility>
#include <numeric>
#include <vector>
#include <array>
#include <set>
#include <queue>
#include <cassert>

template <class T, class U>
inline bool chmin(T &lhs, const U &rhs) {
  if (lhs > rhs) { lhs = rhs; return true; }
  return false;
}

template <class T, class U>
inline bool chmax(T &lhs, const U &rhs) {
  if (lhs < rhs) { lhs = rhs; return true; }
  return false;
}

struct range {
  using itr = int64_t;
  struct iterator {
    itr i;
    constexpr iterator(itr i_) noexcept : i(i_) { }
    constexpr void operator ++ () noexcept { ++i; }
    constexpr itr operator * () const noexcept { return i; }
    constexpr bool operator != (iterator x) const noexcept { return i != x.i; }
  };
  const iterator l, r;
  constexpr range(itr l_, itr r_) noexcept : l(l_), r(std::max(l_, r_)) { }
  constexpr iterator begin() const noexcept { return l; }
  constexpr iterator end() const noexcept { return r; }
};

struct revrange {
  using itr = int64_t;
  struct iterator {
    itr i;
    constexpr iterator(itr i_) noexcept : i(i_) { }
    constexpr void operator ++ () noexcept { --i; }
    constexpr itr operator * () const noexcept { return i; }
    constexpr bool operator != (iterator x) const noexcept { return i != x.i; }
  };
  const iterator l, r;
  constexpr revrange(itr l_, itr r_) noexcept : l(l_ - 1), r(std::max(l_, r_) - 1) { }
  constexpr iterator begin() const noexcept { return r; }
  constexpr iterator end() const noexcept { return l; }
};

#line 2 "/Users/kodamankod/Desktop/Programming/Library/algebraic/modular.cpp"

#include <cstdint>
#line 5 "/Users/kodamankod/Desktop/Programming/Library/algebraic/modular.cpp"

template <uint32_t Modulus>
class modular {
public:
  using value_type = uint32_t;
  using max_type = uint64_t;

  static constexpr value_type mod = Modulus;
  static constexpr value_type get_mod() noexcept { return mod; }
  static_assert(mod >= 2, "invalid mod :: smaller than 2");
  static_assert(mod < (value_type(1) << 31), "invalid mod :: over 2^31");

  template <class T>
  static constexpr value_type normalize(T value_) noexcept {
    if (value_ < 0) {
      value_ = -value_;
      value_ %= mod;
      if (value_ == 0) return 0;
      return mod - value_;
    }
    return value_ % mod;
  }

private:
  value_type value;

public:
  constexpr modular() noexcept : value(0) { }
  template <class T>
  explicit constexpr modular(T value_) noexcept : value(normalize(value_)) { }
  template <class T>
  explicit constexpr operator T() const noexcept { return static_cast<T>(value); }

  constexpr value_type get() const noexcept { return value; }
  constexpr modular operator - () const noexcept { return modular(mod - value); }
  constexpr modular operator ~ () const noexcept { return inverse(); }

  constexpr value_type &extract() noexcept { return value; }
  constexpr modular inverse() const noexcept { return power(mod - 2); }
  constexpr modular power(max_type exp) const noexcept {
    modular res(1), mult(*this);
    while (exp > 0) {
      if (exp & 1) res *= mult;
      mult *= mult;
      exp >>= 1;
    }
    return res;
  }

  constexpr modular operator + (const modular &rhs) const noexcept { return modular(*this) += rhs; }
  constexpr modular& operator += (const modular &rhs) noexcept { 
    if ((value += rhs.value) >= mod) value -= mod; 
    return *this; 
  }

  constexpr modular operator - (const modular &rhs) const noexcept { return modular(*this) -= rhs; }
  constexpr modular& operator -= (const modular &rhs) noexcept { 
    if ((value += mod - rhs.value) >= mod) value -= mod; 
    return *this; 
  }

  constexpr modular operator * (const modular &rhs) const noexcept { return modular(*this) *= rhs; }
  constexpr modular& operator *= (const modular &rhs) noexcept { 
    value = (max_type) value * rhs.value % mod;
    return *this;
  }

  constexpr modular operator / (const modular &rhs) const noexcept { return modular(*this) /= rhs; }
  constexpr modular& operator /= (const modular &rhs) noexcept { return (*this) *= rhs.inverse(); }

  constexpr bool zero() const noexcept { return value == 0; }
  constexpr bool operator == (const modular &rhs) const noexcept { return value == rhs.value; }
  constexpr bool operator != (const modular &rhs) const noexcept { return value != rhs.value; }
  friend std::ostream& operator << (std::ostream &stream, const modular &rhs) {
    return stream << rhs.value;
  }

};

/**
 * @title Modint
 */
#line 2 "/Users/kodamankod/Desktop/Programming/Library/other/fix_point.cpp"

#line 4 "/Users/kodamankod/Desktop/Programming/Library/other/fix_point.cpp"

template <class Func>
struct fix_point: private Func {
  explicit constexpr fix_point(Func &&func): Func(std::forward<Func>(func)) { }
  template <class... Args>
  constexpr decltype(auto) operator () (Args &&... args) const {
    return Func::operator()(*this, std::forward<Args>(args)...);
  }
};

template <class Func>
constexpr decltype(auto) make_fix_point(Func &&func) {
  return fix_point<Func>(std::forward<Func>(func));
}

/**
 * @title Lambda Recursion
 */
#line 60 "main.cpp"

using i32 = int32_t;
using i64 = int64_t;
using u32 = uint32_t;
using u64 = uint64_t;

constexpr i32 inf32 = (i32(1) << 30) - 1;
constexpr i64 inf64 = (i64(1) << 62) - 1;

using m32 = modular<1000000007>;

int main() {
  i32 N;
  std::cin >> N;
  ++N;
  std::vector<std::vector<i32>> base_children(N);
  for (auto i: range(1, N)) {
    i32 p;
    std::cin >> p;
    base_children[p].push_back(i);
  }
  std::vector<i32> depth(N);
  fix_point([&](auto dfs, i32 u, i32 d) -> void {
    depth[u] = d;
    for (auto v: base_children[u]) {
      dfs(v, d + 1);
    }
  })(0, 0);
  i32 root = 0;
  std::set<i32> leaves{ root };
  std::vector<std::set<i32>> children(N);
  std::vector<i32> parent(N, -1);
  m32 ans;
  std::vector<std::pair<m32, m32>> dp(N);
  while (!leaves.empty()) {
    fix_point([&](auto dfs, i32 u) -> void {
      if (children[u].empty()) {
        dp[u].first = dp[u].second = m32(1);
        return;
      }
      m32 sum(1), sec(1);
      dp[u].first = dp[u].second = m32(0);
      for (auto v: children[u]) {
        dfs(v);
        sum *= dp[v].first + dp[v].second;
        sec *= dp[v].second;
      }
      for (auto v: children[u]) {
        dp[u].first += sec / dp[v].second * dp[v].first;
      }
      dp[u].second = sum - dp[u].first;
    })(root);
    ans += dp[root].first * m32(2).power(N - leaves.size());
    std::priority_queue<std::pair<i32, i32>> remove; 
    std::set<i32> new_leaves;
    for (auto u: leaves) {
      for (auto v: base_children[u]) {
        new_leaves.insert(v);
        parent[v] = u;
        children[u].insert(v);
      }
      if (children[u].size() <= 1) {
        remove.emplace(depth[u], u);
      }
    }
    leaves = std::move(new_leaves);
    while (!remove.empty()) {
      auto [d, u] = remove.top();
      remove.pop();
      if (children[u].size() >= 2) {
        continue;
      }
      for (auto v: children[u]) {
        parent[v] = parent[u];
        if (parent[v] != -1) {
          children[parent[v]].insert(v);
        }
        else {
          root = v;
        }
      }
      if (parent[u] != -1) {
        children[parent[u]].erase(u);
        if (children[parent[u]].size() <= 1) {
          remove.emplace(depth[parent[u]], parent[u]);
        }
      }
    }
  }
  std::cout << ans << '\n';
  return 0;
}


Measured memory_bytes: 45408