N = int(input())
A = list(map(int,input().split()))

M = max(A)
C = [0 for i in range(M + 1)]
D = [0 for i in range(M + 1)]

ans = 0
for i in range(N):
  a = A[i]
  for j in range(1,M + 1):
    r = abs(a - j) * (i * C[j] - D[j])
    ans += 2 * r
  C[a] += 1
  D[a] += i
print(ans)