MOD = 998244353

X = int(input())
Y = list(map(int, input().split()))

def count(n):
    val = n * (n + 1) % MOD * (2 * n + 1) % MOD * pow(6, -1, MOD) % MOD
    val += n * (n + 1) % MOD * pow(2, -1, MOD) % MOD
    val *= pow(2, -1, MOD)
    return val % MOD

def sigma(n):
    return n * (n + 1) % MOD * pow(2, -1, MOD) % MOD

ans = 0
for i in range(X):
    for j in range(i + 1, X):
        ans += count(Y[i] + Y[j])
        ans -= count(Y[i] - 1)
        ans -= count(Y[j] - 1)
        ans -= sigma(Y[i]) + sigma(Y[j])
        ans %= MOD

for i in range(X):
    ans += count(Y[i] - 1)

for i in range(X):
    ans += sigma(Y[i])
    ans %= MOD

print(ans)