Buggy python submission (verdict: Time Limit Exceeded):
N=int(input())
S=input()
ans=0

def check(i,j,N,x):
  A = S[j+1:].count(x)
  check_index=i+(j-i)*2
  if check_index<=N-1 and S[check_index]==x:
    A-=1
  return A

for i in range(len(S)-2):
  temp=['']*2
  temp[0]=S[i]
  for j in range(i+1,len(S)-1):
    if S[i]!=S[j]:
      temp[1]=S[j]
    else:
      continue
    if 'R' not in temp:
      ans += check(i,j,N,'R')
    elif 'G' not in temp:
      ans += check(i,j,N,'G')
    elif 'B' not in temp:
      ans += check(i,j,N,'B')
    continue

print(ans)

Fixed submission:
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
import numpy as np
from numba import njit

MOD = 10**9 + 7

N = int(readline())
S = np.array(list(read().rstrip()), np.int8)

R = np.sum(S == ord('R'))
B = np.sum(S == ord('B'))
G = np.sum(S == ord('G'))
 
@njit
def f(S):
    N = len(S)
    ret = 0
    for i in range(N):
        for j in range(i + 1, N):
          k = j + j - i
          if k >= N:
            break
          if S[i] != S[j] and S[i] != S[k] and S[j] != S[k]:
            ret += 1
    return ret
  
answer = R * B * G - f(S)
print(answer)

Buggy python submission (verdict: Time Limit Exceeded):
N=int(input())
S=input()
ans=0
minus=0
for i in range(len(S)-2):
  temp=['']*2
  temp[0]=S[i]
  for j in range(i+1,len(S)-1):
    if S[i]!=S[j]:
      temp[1]=S[j]
    else:
      continue
    if 'R' not in temp:
      ans +=S[j+1:].count('R')
      check_index=i+(j-i)*2
      if check_index<=N-1 and S[check_index]=='R':
        minus+=1
    if 'G' not in temp:
      ans +=S[j+1:].count('G')
      check_index=i+(j-i)*2
      if check_index<=N-1 and S[check_index]=='G':
        minus+=1
    if 'B' not in temp:
      ans +=S[j+1:].count('B')
      check_index=i+(j-i)*2
      if check_index<=N-1 and S[check_index]=='B':
        minus+=1
    continue

print(ans-minus)

Fixed submission:
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
import numpy as np
from numba import njit

MOD = 10**9 + 7

N = int(readline())
S = np.array(list(read().rstrip()), np.int8)

R = np.sum(S == ord('R'))
B = np.sum(S == ord('B'))
G = np.sum(S == ord('G'))
 
@njit
def f(S):
    N = len(S)
    ret = 0
    for i in range(N):
        for j in range(i + 1, N):
          k = j + j - i
          if k >= N:
            break
          if S[i] != S[j] and S[i] != S[k] and S[j] != S[k]:
            ret += 1
    return ret
  
answer = R * B * G - f(S)
print(answer)

Buggy python submission (verdict: Time Limit Exceeded):
N=int(input())
S=input()
ans=0

for i in range(len(S)-2):
  temp=['']*2
  temp[0]=S[i]
  for j in range(i+1,len(S)-1):
    if S[i]!=S[j]:
      temp[1]=S[j]
    else:
      continue
    for k in range(j+1, len(S)):
      if (S[k] not in temp) and (j-i != k-j):
        ans+=1
      else:
        continue
print(ans)

Fixed submission:
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
import numpy as np
from numba import njit

MOD = 10**9 + 7

N = int(readline())
S = np.array(list(read().rstrip()), np.int8)

R = np.sum(S == ord('R'))
B = np.sum(S == ord('B'))
G = np.sum(S == ord('G'))
 
@njit
def f(S):
    N = len(S)
    ret = 0
    for i in range(N):
        for j in range(i + 1, N):
          k = j + j - i
          if k >= N:
            break
          if S[i] != S[j] and S[i] != S[k] and S[j] != S[k]:
            ret += 1
    return ret
  
answer = R * B * G - f(S)
print(answer)