why does it show 'builtin_function_or_method' object is not subscriptable' in the if condition?

Line 3 the if condition throws error "builtin_function_or_method' object is not subscriptable".What should be the correct syntax here? for i in range(0,n-1,1): for j in range(i, n, 1): if (sum[j]-sum[i])==(prod[j]/prod[i]): count+=1 print(count)