#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 998244353;
// constexpr int MOD = 1000000007;
constexpr int DY4[]{1, 0, -1, 0}, DX4[]{0, -1, 0, 1};
constexpr int DY8[]{1, 1, 0, -1, -1, -1, 0, 1};
constexpr int DX8[]{0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U>
inline bool chmax(T& a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U>
inline bool chmin(T& a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    std::cin.tie(nullptr);
    std::ios_base::sync_with_stdio(false);
    std::cout << fixed << setprecision(20);
  }
} iosetup;

int main() {
  constexpr int A = 500;
  int n; cin >> n;
  vector<int> a(n);
  for (int& a_i : a) cin >> a_i;
  array<int, A + 1> num{};
  array<ll, A + 1> sum_ai{}, sum_i{}, i_ai{};
  REP(i, n) {
    ++num[a[i]];
    sum_ai[a[i]] += a[i];
    sum_i[a[i]] += i;
    i_ai[a[i]] += ll{i} * a[i];
  }
  ll ans = 0;
  REP(i, n) {
    --num[a[i]];
    sum_ai[a[i]] -= a[i];
    sum_i[a[i]] -= i;
    i_ai[a[i]] -= ll{i} * a[i];
    REP(j, a[i]) {
      ans -= ll{i} * a[i] * num[j];
      ans -= i_ai[j];
      ans += sum_i[j] * a[i];
      ans += sum_ai[j] * i;
    }
    FOR(j, a[i] + 1, A + 1) {
      ans += ll{i} * a[i] * num[j];
      ans += i_ai[j];
      ans -= sum_i[j] * a[i];
      ans -= sum_ai[j] * i;
    }
  }
  cout << ans * 2 << '\n';
  return 0;
}