Buggy python submission (verdict: Time Limit Exceeded):
import sys
readline = sys.stdin.buffer.readline

def make_modinv_list(n, mod=10**9+7):
    inv_list = [0]*(n+1)
    inv_list[1] = 1
    for i in range(2, n+1):
        inv_list[i] = (mod - mod//i * inv_list[mod%i] % mod)
    return inv_list

mod = 998244353
N = int(readline())
A = list(map(int, readline().split()))
C = max(A) + 1
inv_list = make_modinv_list(C, mod)
h = [0] * C
for x in A:
    h[x] = (h[x] + x) % mod
for i in range(1, C):
    for j in range(i*2, C, i):
        h[i] = (h[i] + h[j]) % mod
g = [0] * C
for i in range(1, C):
    g[i] = h[i] * h[i] % mod
for i in range(C-1, 0, -1):
    for j in range(i*2, C, i):
        g[i] = (g[i] - g[j]) % mod
ans = 0
for i in range(1, C):
    ans = (ans + g[i] * inv_list[i]) % mod
ans -= sum(A)
print(ans * inv_list[2] % mod)    


Fixed submission:
import sys

readline = sys.stdin.readline

ns = lambda: readline().rstrip()
ni = lambda: int(readline().rstrip())
nm = lambda: map(int, readline().split())
nl = lambda: list(map(int, readline().split()))

def modinv(x, mod):
    a, b = x, mod
    u, v = 1, 0
    while b:
        t = a // b
        a -= t * b; a, b = b, a
        u -= t * v; u, v = v, u
    return u % mod

def solve():
  n = ni()
  a = nl()
  m = max(a)
  mod = 998244353
  l = [0]*(m+1)
  for x in a:
    l[x] += x
  sieve = [1]*(m+1)
  sieve[0] = sieve[1] = 0
  for i in range(2, m+1):
    if sieve[i]:
      for j in range(m//i, 0, -1):
        sieve[j*i] = 0
        l[j] += l[j*i]
      sieve[i] = 1
  for i in range(m+1):
    l[i] = l[i] * l[i] % mod
  for i in range(2, m+1):
    if sieve[i]:
      for j in range(1, m//i + 1):
        l[j] -= l[j*i]
  s = -sum(a)
  for i in range(1, m+1):
    if l[i]:
      s = (s + l[i] * modinv(i, mod)) % mod
  print(s * modinv(2, mod) % mod)
  return

solve()

Buggy python submission (verdict: Time Limit Exceeded):
import sys
readline = sys.stdin.buffer.readline

def make_modinv_list(n, mod=10**9+7):
    inv_list = [0]*(n+1)
    inv_list[1] = 1
    for i in range(2, n+1):
        inv_list[i] = (mod - mod//i * inv_list[mod%i] % mod)
    return inv_list

mod = 998244353
N = int(readline())
A = list(map(int, readline().split()))
C = max(A) + 1
inv_list = make_modinv_list(C, mod)
h = [0] * C
l = [0] * C
for x in A:
    h[x] = (h[x] + x) % mod
    l[x] = (l[x] + x**2) % mod
for i in range(1, C):
    for j in range(i*2, C, i):
        h[i] = (h[i] + h[j]) % mod
        l[i] = (l[i] + l[j]) % mod
inv2 = inv_list[2]
g = [(h[i]**2 - l[i]) * inv2 % mod for i in range(C)]
for i in range(C-1, 0, -1):
    for j in range(i*2, C, i):
        g[i] = (g[i] - g[j]) % mod
ans = 0
for i in range(1, C):
    ans = (ans + g[i] * inv_list[i]) % mod
print(ans)    


Fixed submission:
import sys

readline = sys.stdin.readline

ns = lambda: readline().rstrip()
ni = lambda: int(readline().rstrip())
nm = lambda: map(int, readline().split())
nl = lambda: list(map(int, readline().split()))

def modinv(x, mod):
    a, b = x, mod
    u, v = 1, 0
    while b:
        t = a // b
        a -= t * b; a, b = b, a
        u -= t * v; u, v = v, u
    return u % mod

def solve():
  n = ni()
  a = nl()
  m = max(a)
  mod = 998244353
  l = [0]*(m+1)
  for x in a:
    l[x] += x
  sieve = [1]*(m+1)
  sieve[0] = sieve[1] = 0
  for i in range(2, m+1):
    if sieve[i]:
      for j in range(m//i, 0, -1):
        sieve[j*i] = 0
        l[j] += l[j*i]
      sieve[i] = 1
  for i in range(m+1):
    l[i] = l[i] * l[i] % mod
  for i in range(2, m+1):
    if sieve[i]:
      for j in range(1, m//i + 1):
        l[j] -= l[j*i]
  s = -sum(a)
  for i in range(1, m+1):
    if l[i]:
      s = (s + l[i] * modinv(i, mod)) % mod
  print(s * modinv(2, mod) % mod)
  return

solve()

Buggy python submission (verdict: Time Limit Exceeded):
import sys

readline = sys.stdin.readline

ns = lambda: readline().rstrip()
ni = lambda: int(readline().rstrip())
nm = lambda: map(int, readline().split())
nl = lambda: list(map(int, readline().split()))

def make_modinv_list(n, mod=10**9+7):
    inv_list = [0]*(n+1)
    inv_list[1] = 1
    for i in range(2, n+1):
        inv_list[i] = (mod - mod//i * inv_list[mod%i] % mod)
    return inv_list

def solve():
  mod = 998244353
  n = ni()
  a = nl()
  m = max(a)
  s = -sum(a) % mod
  l = [0]*(m+1)
  for x in a:
    l[x] += x
  a = make_modinv_list(m, mod)
  sieve = [1]*(m+1)
  sieve[0] = sieve[1] = 0
  for i in range(2, m+1):
    if sieve[i]:
      for j in range(m//i, 0, -1):
        sieve[j*i] = 0
        l[j] += l[j*i]
      sieve[i] = 1
  for i in range(m+1):
    l[i] = l[i] * l[i] % mod
  for i in range(2, m+1):
    if sieve[i]:
      for j in range(1, m//i + 1):
        l[j] = (l[j] - l[j*i]) % mod
  for i in range(1, m+1):
    if l[i]:
      s = (s + l[i] * a[i]) % mod
  print(s * a[2] % mod)
  return

solve()

Fixed submission:
import sys

readline = sys.stdin.readline

ns = lambda: readline().rstrip()
ni = lambda: int(readline().rstrip())
nm = lambda: map(int, readline().split())
nl = lambda: list(map(int, readline().split()))

def modinv(x, mod):
    a, b = x, mod
    u, v = 1, 0
    while b:
        t = a // b
        a -= t * b; a, b = b, a
        u -= t * v; u, v = v, u
    return u % mod

def solve():
  n = ni()
  a = nl()
  m = max(a)
  mod = 998244353
  l = [0]*(m+1)
  for x in a:
    l[x] += x
  sieve = [1]*(m+1)
  sieve[0] = sieve[1] = 0
  for i in range(2, m+1):
    if sieve[i]:
      for j in range(m//i, 0, -1):
        sieve[j*i] = 0
        l[j] += l[j*i]
      sieve[i] = 1
  for i in range(m+1):
    l[i] = l[i] * l[i] % mod
  for i in range(2, m+1):
    if sieve[i]:
      for j in range(1, m//i + 1):
        l[j] -= l[j*i]
  s = -sum(a)
  for i in range(1, m+1):
    if l[i]:
      s = (s + l[i] * modinv(i, mod)) % mod
  print(s * modinv(2, mod) % mod)
  return

solve()

Buggy python submission (verdict: Time Limit Exceeded):
import sys

readline = sys.stdin.readline

ns = lambda: readline().rstrip()
ni = lambda: int(readline().rstrip())
nm = lambda: map(int, readline().split())
nl = lambda: list(map(int, readline().split()))

def modinv(x, mod):
    a, b = x, mod
    u, v = 1, 0
    while b:
        t = a // b
        a -= t * b; a, b = b, a
        u -= t * v; u, v = v, u
    return u % mod

def solve():
  n = ni()
  a = nl()
  m = max(a)
  mod = 998244353
  l = [0]*(m+1)
  for x in a:
    l[x] += x
  sieve = [1]*(m+1)
  sieve[0] = sieve[1] = 0
  for i in range(2, m+1):
    if sieve[i]:
      for j in range(m//i, 0, -1):
        sieve[j*i] = 0
        l[j] += l[j*i]
      sieve[i] = 1
  for i in range(m+1):
    l[i] = l[i] * l[i] % mod
  for i in range(2, m+1):
    if sieve[i]:
      for j in range(1, m//i + 1):
        l[j] -= l[j*i]
  s = -sum(a)
  for i in range(1, m+1):
    if l[i]:
      s = (s + l[i] * modinv(i, mod)) % mod
  print(s * modinv(2, mod) % mod)
  return

solve()

Fixed submission:
import sys

readline = sys.stdin.readline

ns = lambda: readline().rstrip()
ni = lambda: int(readline().rstrip())
nm = lambda: map(int, readline().split())
nl = lambda: list(map(int, readline().split()))

def modinv(x, mod):
    a, b = x, mod
    u, v = 1, 0
    while b:
        t = a // b
        a -= t * b; a, b = b, a
        u -= t * v; u, v = v, u
    return u % mod

def solve():
  n = ni()
  a = nl()
  m = max(a)
  mod = 998244353
  l = [0]*(m+1)
  for x in a:
    l[x] += x
  sieve = [1]*(m+1)
  sieve[0] = sieve[1] = 0
  for i in range(2, m+1):
    if sieve[i]:
      for j in range(m//i, 0, -1):
        sieve[j*i] = 0
        l[j] += l[j*i]
      sieve[i] = 1
  for i in range(m+1):
    l[i] = l[i] * l[i] % mod
  for i in range(2, m+1):
    if sieve[i]:
      for j in range(1, m//i + 1):
        l[j] -= l[j*i]
  s = -sum(a)
  for i in range(1, m+1):
    if l[i]:
      s = (s + l[i] * modinv(i, mod)) % mod
  print(s * modinv(2, mod) % mod)
  return

solve()