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

n = int(input())
s = str(input())

r = {}
b = {}
g = {}
for i in range(len(s)):
    if s[i] == 'R':
        r[i] = s[i]
    elif s[i] == 'B':
        b[i] = s[i]
    else:
        g[i] = s[i]

ans = len(r) * len(b) * len(g)

nums = list(itertools.product(r.keys(), b.keys(), g.keys()))

for n in nums:
    num = list(n)
    num.sort()
    if num[2] - num[1] == num[1] - num[0]:
        ans -= 1

#print(r.keys())
#print(b.keys())
##print(g.keys())
#for i in r.keys():
#    for j in b.keys():
#        for k in g.keys():
#            if abs(k -j) == abs(j -i) or abs(k-i) == abs(i-j) or abs(k-j) == abs(k-i) :
#                ans -= 1


print(ans)

Fixed submission:
import itertools
n = int(input())
s = str(input())
r = {}
b = {}
g = {}
for i in range(len(s)):
    if s[i] == 'R':
        r[i+1] = s[i]
    elif s[i] == 'B':
        b[i+1] = s[i]
    else:
        g[i+1] = s[i]
ans = len(r) * len(b) * len(g)
for i in r.keys():
    for j in b.keys():
        diff = abs(j-i)
        minb = min(i,j)-diff
        maxb = max(i,j)+diff
        if maxb in g.keys():
            ans -= 1
        if minb in g.keys():
            ans -= 1
        if((i+j)%2==0):
            if((i+j)//2 in g.keys()):
                ans -=1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):

n = int(input())
s = str(input())

r = {}
b = {}
g = {}
for i in range(len(s)):
    if s[i] == 'R':
        r[i] = s[i]
    elif s[i] == 'B':
        b[i] = s[i]
    else:
        g[i] = s[i]

ans = len(r) * len(b) * len(g)

for i in r.keys():
    for j in b.keys():
        for k in g.keys():
            if abs(k -j) == abs(j -i) or abs(k-i) == abs(i-j) or abs(k-j) == abs(k-i) :
                ans -= 1


print(ans)

Fixed submission:
import itertools
n = int(input())
s = str(input())
r = {}
b = {}
g = {}
for i in range(len(s)):
    if s[i] == 'R':
        r[i+1] = s[i]
    elif s[i] == 'B':
        b[i+1] = s[i]
    else:
        g[i+1] = s[i]
ans = len(r) * len(b) * len(g)
for i in r.keys():
    for j in b.keys():
        diff = abs(j-i)
        minb = min(i,j)-diff
        maxb = max(i,j)+diff
        if maxb in g.keys():
            ans -= 1
        if minb in g.keys():
            ans -= 1
        if((i+j)%2==0):
            if((i+j)//2 in g.keys()):
                ans -=1
print(ans)

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

n = int(input())
s = str(input())

a = list(itertools.combinations(range(1,n+1),3))

ans = 0
for i in a:
    if (s[i[0]-1] != s[i[1]-1] and  s[i[2]-1] != s[i[1]-1] and  s[i[0]-1] != s[i[2]-1] and (i[2]-i[1] != i[1] - i[0])):
        #print(i)
        ans +=1

print(ans)

Fixed submission:
import itertools
n = int(input())
s = str(input())
r = {}
b = {}
g = {}
for i in range(len(s)):
    if s[i] == 'R':
        r[i+1] = s[i]
    elif s[i] == 'B':
        b[i+1] = s[i]
    else:
        g[i+1] = s[i]
ans = len(r) * len(b) * len(g)
for i in r.keys():
    for j in b.keys():
        diff = abs(j-i)
        minb = min(i,j)-diff
        maxb = max(i,j)+diff
        if maxb in g.keys():
            ans -= 1
        if minb in g.keys():
            ans -= 1
        if((i+j)%2==0):
            if((i+j)//2 in g.keys()):
                ans -=1
print(ans)