I have difficulties using `NumPy` and/or `Pandas` for working with a `2D` list to:

1. Get the `sum` of unique combination of all elements without choosing from same row again (it should be 81 combinations for the array below).
2. Print the row and column of the each element in the combination.

For example: 

```
arr = [[1, 2, 4], [10, 3, 8], [16, 12, 13], [14, 4, 20]]

(1,3,12,20), Sum = 36 and (row, col) =  [(0,0),(1,1),(2,1),(3,2)]

(4,10,16,20), Sum = 50 and (row, col) =[(0,2),(1,0),(2,0),(3,2)]

```