# How to generate the combinations of an array and divide the numbers in each combination by the product of the numbers in the same combination?

Given an array of N size, I want to return all possible permutations of the array. For each permutation of the array I want to return the value of each number in that combination divided by the sum of the other numbers in the combination including the dividend.

Example: Give the array 123, you find all the possible combinations which are (1,2) (1,3) (2,3) (1,2,3). You then take each combination and divide it as such: (1,2) = (1/1+2) = .33333. (2,1) = (2/1+2) = .66666.

```import math
import itertools
from itertools import combinations
import numpy as np
n = int(input("Enter The Amount of Numbers in the List: ")
)
z = []
q = []
for i in range(0,n):
x = float(input("Enter the numbers: "))
q.append(x)
h = n+1

permutation_list = []
for i in range(1, len(q)+1):
permutations = combinations(q, i)
for perm in permutations:
perm_prod = 1
for j in range(len(perm)):
perm_prod *= perm[j]
for j in range(len(perm)-1):
for k in range(1,len(perm)):
prod_without_this = perm[j]+perm[k]
this_num_div_other_nums = perm[j] / prod_without_this
second_num = perm[k] / prod_without_this
permutation_list.append(this_num_div_other_nums)
permutation_list.append(second_num)
permutation_list[h:]
print(permutation_list)
```

This is what I have so far but I am having trouble dividing with combinations with length greater than 2. Any help would be appreciated.

You could do something like this, where you loop over each combination for each element in the combo.

```from itertools import combinations, chain

l = [1,2,3]

c = list(chain.from_iterable([list(combinations(l,i)) for i in range(2,len(l)+1)]))

results = []
for x in c:
for n in range(len(x)):
results.append(x[n]/sum(x))
```

Results

```[0.3333333333333333,
0.6666666666666666,
0.25,
0.75,
0.4,
0.6,
0.16666666666666666,
0.3333333333333333,
0.5]
```